The M25

Britain came late to motorways. It was only in 1959, long after Germany’s autobahns and the United States’ parkway-building programmes had taken shape, that Britain finally started developing its own version. The M25 orbital, London’s distinctive contribution to motorway building, came even later. It may owe something to Washington DC’s Beltway, or the Boulevard Périphérique in Paris, but it is the largest of its kind in Europe and serves to define the shape and the identity of the city.

The M25 is the product of an endlessly drawn-out planning process. The original idea was to restructure London around a set of four concentric motorway boxes that would have seen the wholesale destruction of swathes of historic buildings in Covent Garden and family homes in the inner suburbs. After a massive protest campaign the bulldozers were called off, and only the least destructive, outermost ring was completed.

It took 15 years to finish the 117 miles of the M25 that now define London. The road does not reflect political or geographical boundaries but, by default, sums up London as a post-industrial city, an amorphous sprawl that spans ancient settlements and open space, business parks and out-of-town shopping malls, binding them together into a more-or-less coherent single entity.

Yet the M25 has had the effect of generating, rather than taming, traffic. From its original six lanes, it has fattened into eight and then 10. There was even a plan to widen the section near Heathrow to 14 lanes.

Blue plaques

There are now nearly 900 plaques affixed to buildings in London, recording their association with notable individuals. They date back to 1867 and a scheme put forward by the Royal Society of Arts and enthusiastically endorsed by Henry Cole, father of the Crystal Palace and the Victoria and Albert Museum. The oldest surviving sign marks the house in Covent Garden in which an exiled Napoleon III lived until he returned to Paris.

Others commemorate an extraordinary range of individuals, from Karl Marx in Soho and Friedrich Engels in Primrose Hill, to Vivien Leigh, Mozart and Handel. There is a suburban semi-detached house with a memorial to the first British soldier to enter the gates of the liberated Auschwitz. A plaque on the side of New Zealand House commemorates the communist revolutionary prime minister Ho Chi Minh, who before returning to Vietnam worked as a waiter in a restaurant that once stood on the site.

They are generally called “blue plaques”, though in the early days they could be terracotta coloured. They have been successfully administered by the London County Council, the Greater London Council and English Heritage. For many years the ceramic was manufactured by Royal Doulton; more recently, they have been made by individual craftspeople.

In 1991 the Royal College of Art refused Gavin Turk a degree on the basis that his final show, Cave, consisted of a whitewashed studio space containing only a blue heritage plaque commemorating his own presence: “GAVIN TURK Sculptor worked here 1989–1991.”

The Barbican

Conceived out of the rubble of the second world war, the Barbican was central London’s biggest single attempt at the grand gesture of modernist planning. The City of London, the shadowy but powerful entity with an electorate so small that the usual tribulations of democratic politics do not apply, set about the reconstruction of an area on the northern edge of the Square Mile that had once been the parade ground of Roman legionaries. The idea was to combine a new residential community, crowned by three high-rise apartment towers, with a whole range of cultural amenities, as well as public open spaces and the City’s school for girls.

Designed by the architectural practice Chamberlin, Powell and Bon, one of the foremost proponents of modernism in post-war Britain, the Barbican is a remarkable exercise in high-density urbanism. The architects used exposed concrete throughout – usually a bleak material, but by giving the towers a bold geometry based on a triangular plan as well as projecting balconies, they managed to create a picturesque silhouette for the development when seen against the skyline.

The Barbican has since withstood the whims of architectural fashion, the hard-to-navigate confusion of its art gallery, concert hall and theatre, and even a bad case of leaking flat roofs, to win over a sceptical London public.

Time Out

Time Out magazine is a reminder of London’s radical 1960s. In a fit of hippy utopianism, Tony Elliott started it as a collective in 1968 with the aim of publishing listings of all things groovy every fortnight. It covered T Rex (in their acoustic phase) playing at the Roundhouse, and Pink Floyd at the Middle Earth, a psychedelic club that opened in Covent Garden before the vegetable market had moved out.

Time Out was quick to list gay and lesbian venues and to cover radical politics, and it rarely sold more than 5,000 copies. By the 1970s it was becoming more business-like, but to do so it had to survive a bruising strike by its original staff, their launch of a left-wing alternative (City Limits) when they decided to abandon the strike, and an opportunistic and short-lived commercial competitor launched by Richard Branson.

It was during this period that the graphic designer Pearce Marchbank gave Time Out its distinctive identity, in particular its masthead, that now appears on editions (some licensed, others subsidiaries) that appear around the world. Time Out gave a certain kind of London a sense of itself, making a shared view of the city visible. The magazine both reflected and helped to shape the London of its day.

The original London edition continues to flourish, in a new incarnation since 2012 as a free listings magazine, shorn of politics and handed out at every Tube station.

Tower Bridge

There is nothing else in the world quite like Tower Bridge, built 1886–1894. It is the product of the very particular circumstances of London at the end of the 19th century, when the Thames was full of shipping from all over the world and the city’s population had doubled in four decades.

A new crossing to link the north and south banks, just to the east of the Tower of London – to ease congestion on existing bridges – had been in discussion ever since 1870. The difficulty was how to thread it through one of the busiest ports in the world without disturbing the shipping. A bridge high enough to allow tall ships under it was suggested by Sir Joseph Bazalgette, but that would have needed a 1,524-metre long spiralling ramp.

The most practical solution was a bridge that could be opened and closed with hydraulic power. But because the Thames Conservancy insisted the bridge be opened for two hours each day, there was also a need for a high-level pedestrian walkway. That, and the fact that the Crown insisted that the bridge reflected the architecture of the Tower of London, accounts for the remarkable silhouette of the bridge.

Inside the crenellations and turrets of the granite skin is a steel structure – entertainingly revealed in one of the more imaginative sequences of Guy Ritchie’s Sherlock Holmes (2009). The hydraulics are capable of opening the bridge in less than five minutes, which made the high-level walkway redundant.

The wharves upstream of the bridge have gone, too. What is left is a remarkable monument to what London once was, and an internationally recognisable logo for the city as it is today.

59 Brick Lane

What is now a mosque at 59 Brick Lane was once a synagogue and, before that, a Methodist chapel. It was originally built as a Huguenot place of worship in 1743. If one single building can represent the essence of London’s cultural diversity of three centuries, this is it.

Brick Lane, now the centre of the city’s Bangladeshi community, was once an area of weavers’ lofts – domestic family factories run by French Huguenots, Protestant refugees from France’s murderous Wars of Religion. Their presence lingers only in a few additions to the area’s 18th-century houses, built to accommodate their looms, and in the form of this brick building on the corner of Brick Lane and Fournier Street.

It has a minaret now and is operated as a mosque, but it was built by the French in a plain-but-handsome brick style. In between its life as a chapel and as a mosque it was, for more than a century, a synagogue – established by Eastern European Jews fleeing Russian pogroms.

The transformation of this one building is mirrored by that of the city around it. Street signs are now rendered in Bengali, even as the 18th-century weavers’ houses have been restored by wealthy newcomers, as the city’s financial centre presses ever eastward into Spitalfields.

Fulcrum, by Richard Serra

The Broadgate development took what had once been two Victorian railway stations, Liverpool Street and Broad Street, and transformed them into 370,000 square metres of prime office space. It was a project that played an important part in making life difficult for the developers of Canary Wharf. It was also notable for the quality of its architecture – initiated by the late Peter Foggo of Arup Associates, then taken forward by the US firm Skidmore, Owings & Merrill (SOM) – and its public spaces featuring travertine and bronze and even a skating rink.

By an impressive sleight of hand, the authorities were persuaded to allow a change in the postcode boundaries – giving the offices a vital EC postal code that signified prime financial territory, rather than fringe.

Broadgate is also the scene of one of London’s very few pieces of wholly convincing public art. When the City of London’s financial core was expanded northward, Richard Serra was commissioned to make an artwork that reflected the civic ambition of the project. The result, Fulcrum, comprises five sheets of Cor-Ten steel, 17 metres high.

Regent’s Park

The Regent’s Park began as a huge residential property speculation in the early years of the 19th century. It has since become a key part of London’s most essential feature: its network of parks, which today makes it one of Europe’s greenest capitals.

Conceived by John Nash for his patron, the Prince Regent, the Regent’s Park is a defining piece of picturesque city planning. It was intended to give London the impetus to leap across the Marylebone Road and expand towards its northern suburbs.

The park was to be edged by a series of grand, stucco-faced terraces that gave individual houses the aspect of a palace. Nash designed a number of the terraces himself, deploying giant classical orders, pediments and rooftop sculpture. However, much of the housing was in fact built by developers who had bought up the surrounding plots of land. Some of these deliberately flouted Nash’s stylistic guidelines, which accounts for the sudden shift from sandstone French Empire style, to white stucco classicism, to grey-brick gothic along the eastern edge.

London Zoo occupies the northern edge of the park. And in recent years the park has become home to the annual Frieze art fair, with its sequence of architect-designed tents.

Tube map

London is defined and given shape and identity by the map of its underground railway system. The Metropolitan line began operating in 1863, with open coaches drawn by coal-burning, steam-powered locomotives running between Paddington and Aldgate East. It took Paris 50 years to catch up.

What had started out as a cluster of privately owned underground lines turned, in the early 20th century, into a municipal, coherently run system under the direction of Frank Pick. Described by the architectural historian Nikolaus Pevsner as “a modern Medici”, Pick commissioned austere new stations from Charles Holden, an elegant font designed by Edwin Johnston, a distinctive circle and bar logotype, and posters by everybody from Edward McKnight Kauffer to László Moholy-Nagy.

But perhaps the most powerful achievement was the London Underground map – a diagram, really – produced not by a designer at all but by Harry Beck, an engineering draughtsman working in London Transport’s signals office.

From 1933 onward, the new Underground map created the mental image of what London is – a symbol, but also a means of understanding how to navigate the city. There is something of Beck’s background in drawing electrical circuit diagrams in the way that the interchanges are described by open circles, but the real insight was the way in which the river Thames appears on the map – a reminder of actual geography that roots the diagram in reality.

It was the point of departure for every other subway system map in the world. Massimo Vignelli’s work for New York’s subway system had much more gorgeous citrus colours, but lasted less than five years. Beck’s work has inspired artists and attracted the attention of Marxist-leaning design historians, who have suggested the diagram was used by unscrupulous house builders to suggest that the new housing estates they were throwing up around the stations at the end of the lines were much closer to the city centre than they actually were.

Routemaster bus

Who would have believed a commitment to resurrecting London’s double-decker buses could underpin a mayoral election campaign? Boris Johnson’s years in office are marked by fiascos such as the almost unused cable car crossing from the Greenwich Peninsula. The so-called “Boris bikes” were mooted by his predecessor, Ken Livingstone, and based on what Paris had already done. But there is one London symbol for which Johnson is undoubtedly responsible: the Thomas Heatherwick-designed new Routemaster.

On Livingstone’s watch, Transport for London replaced its Routemaster fleet – designed and built specifically for the city – with a German import, a single-deck coach dismissively referred to as the “bendy bus” that was so long it often blocked crossroads. Johnson committed himself to a modernised Routemaster, which he pitched as an essential part of the city’s identity.

The original Routemaster bus was prototyped in 1954. Mechanically, it was the work of a team led by London Transport’s chief engineer, Albert Arthur Molteno Durrant (who designed tanks during the second world war), Eric Ottoway and Colin Curtis. They used an aluminium body, power steering and an automatic gearbox that made it much lighter and easier to drive than its predecessors, even though it accommodated 64 passengers, eight more than the model it replaced.

But it was the industrial designer Douglas Scott, brought in as a consultant to style it, who made it such a charismatic distillation of London; one that still looks contemporary when it makes an occasional appearance on the city’s heritage routes.

Scott had worked for Raymond Loewy and restyled the Aga. He was determined that his bus would not look like a shoebox, as he put it, and gave it subtle tapered lines and curved edges. The interior was to project comfort and quality. The two decks were called “saloons” and had what Scott called “burgundy” lining panels, “Chinese green” window surrounds and “Sung yellow” ceilings. The seats had a specially designed tartan moquette with leather edges, and there was a bell on a rope and a special box for used tickets.

London in Fifty Design Icons by Deyan Sudjic & The Design Museum is published by Conran Octopus (£12.99). Follow Guardian Cities on Twitter and Facebook and join the discussion