Beauty of bus depots: The Design Museum celebrates London's overlooked architectural gems

Every city has them. Buildings you walk past a thousand times without noticing. Most are ignored, some are derided, others you might not know exist or are buried underneath your feet. Others are recognised for their beauty but are closed. Lesser Known Architecture, an exhibition at the Design Museum, aims to celebrate these structures.

Some of Britain's top architecture experts have nominated their London favourites, from the filigree ironwork at South Kensington Tube station to the six-mile subterranean Post Office Railway and the concrete diamond exoskeleton of Welbeck Street car park, which is tucked behind Selfridges and, according to Sam Jacob, director of FAT Architecture, ought to be "regarded along with other great structures occurring at the intersection of transport and architecture, such as Gilbert Scott's St Pancras, Brunel's train sheds and Grand Central Station".

Theo Simpson's photographs capture them all with the kind of municipal colour offset that paradoxically emphasises both their (often) Modernist utility and the beauty found in the overlooked.

Lesser Known Architecture, Design Museum, London SE1 (020 7940 8790; designmuseum.org) 4 June to 22 July 2013

STOCKWELL BUS GARAGE

London – unlike New York – may well sleep, but its dreams are kept in motion by its vast fleet of buses. Only those who drive them or fall asleep, drunk on the back of the top deck, really get to see inside their temporary resting places.

There are dozens of these giant hangars in the capital, many of little architectural note beyond the curious phenomenon of peeking in to see the sleeping rows of empty buses.

But Stockwell, a hulking beauty whose grasping concrete arches (spawned by a lack of steel) reach magnificently over its fleet of parked 11s, 19s and 333s, was once the largest unsupported area under a single roof in Europe.

Nominated by: Tom Dyckhoff, presenter, The Culture Show

"In the 1950s... we still built bus garages like palaces for the ordinary man on the Clapham omnibus. Quite literally, in this case. Bus garages mind. Stockwell Bus Garage isn't even a station, it's a depot."

BEVIN COURT, ISLINGTON

Along with the "Please Please Me" stairs inside EMI's building in Manchester Square, Bevin Court's stairs must be the most famous in that rather niche sub-category of "staircases photographed from below".

This fan-shaped 1950s Berthold Lubetkin block was to be named after Lenin (it occupies the site of his former home while he was exiled in London in 1902), but that and its budget changed and the main act of architectural grandeur remains its central spoke of a staircase.

The writer John Allan said: "It is difficult to cite any public staircase in the whole Modern movement that can rival Lubetkin's masterpiece".

Nominated by Tom Dyckhoff

"Most staircases in post-war blocks of flats are nothing to write home about. This one, though, [is] plucked from an Escher print... Imagine going home to this. Imagine popping out for a pint of milk."

BROWNFIELD ESTATE, POPLAR

Nestled next to the northern approach to the Blackwall Tunnel in east London, the Brownfield Estate and its landmark, the 27-storey Balfron Tower, remain a signature work of Ernö Goldfinger. He later perfected the Brutalist public-housing trick with the Trellick Tower in North Kensington. Goldfinger's colleague James Dunnett used the term a "delicate sense of terror" when referring to the Balfron. It's in the process of regeneration, but Goldfinger's brutal village will retain its character regardless.

Nominated by Owen Hatherley, architecture writer

"The Brownfield estate as a whole is still remarkable as an example of a time when public housing could be valued as much, or rather more, than any other form of building."

CRYSTAL PALACE SUBWAY

While the charred glass of Paxton's vast exhibition space is perhaps the best known of London's lost architecture, the Palace's 1865 public subway might be the most intriguing. A bricked wonder built by Italian craftsmen overseen by Edward Middleton Barry (who designed the Royal Opera House), it has been closed to the public for 20 years (a campaign to reopen it continues) but once provided access from the railway to the grounds of the Palace without the need to cross filthy Victorian roads.

Nominated by Rory Olcayto, deputy editor, The Architects' Journal

"An extraordinary pedestrian underpass of octagonal columns fashioned from cream and orange brickwork. It is one of the few elements of the vast exhibition complex to have survived the great inferno of 1936."

CABMEN'S SHELTERS

The Baader-Meinhof Phenomenon of London geography. You can spend years wandering around the city without even noticing one, but once you do, it seems like they're everywhere. In fact there are only 13 left in the city. These Victorian green boxes spread across London in the late 19th century to provide food, drink and shelter for London's thousands of horse-drawn cab drivers and remained in the age of the car. Inside, they feature just two narrow benches and, usually, tea and bacon sarnie making facilities. Sadly, unless you're a cabbie, you're unlikely to be welcome.

Nominated by Oliver Wainwright, architecture critic

"Like a cross between a quaint country cricket pavilion and a large garden shed, the cabmen's shelter is an enigmatic part of the London streetscape. It squats at the side of the road like an emerald Tardis."