Courtesy Hogarth Architects
Hogarth Architects-designed Hidden House's huge finished basement, light-up dance floor and waterfall were featured on the British homes show "Grand Designs."
Hamish Par
The windows at Villa Caroisla (Nick Baker Architects) are meant to frame the view outside as though it were a living piece of art.
Iwan Baan
A former carpet factory, Second Home is now a workspace and incubator for creative nomads, and a venue for private events.
Anthony Coleman/Open House London
Once a 1930s milk depot, Quay House was converted into an architect's studio and home in 2001.
Courtesy Open House London
Designed by Brutalist architect Basil Spence, the library was refurbished in 2016.
Courtesy Open House London
The residence of the British Prime Minister since 1735, some of the most important decisions in domestic and world politics have been made behind its imposing black door. It's safe to say there isn't a nook or cranny which hasn't witnessed some moment of history. Tours are by public ballot and photo ID is required.
AFP/AFP/AFP/Getty Images
The Grade I listed Victorian building was previously home to the Foreign Office, the India Office, the Colonial Office and the Home Office. These days the Italianate style complex is the Foreign and Commonwealth Office, with its majestic Durbar Court proving a perennial highlight for visitors.
James O. Davies/English Heritage
Designed by Ernö Goldfinger, the godfather of British modernist architecture, Trellick Tower drew from Le Corbusier's Unite d'Habitation. With Brutalism back on the map, it will no doubt prove a popular retro entry on the list of attractions.
Dennis Gilbert/VIEW/Dennis Gilbert/VIEW
Part of the London School of Economics and Political Science, the Saw Swee Hock Student Centre was nominated for the Stirling Prize in 2014.
Courtesy of The View from The Shard
Renzo Piano's Shard towers over London's skyline as the tallest building in Western Europe. The 306-meter (1004-foot) skyscraper will open up its viewing platform on Level 72 -- 244 m (801 ft) above ground -- for 50 people a day, chosen via a public ballot.
Gherkin Oli Scarff/Getty Image
Affectionately known as "The Gherkin," 30 St Mary Axe is among the major London skyscrapers opening its doors. Visitors have a chance to tour the foyer and top floor of the 40-story curvilinear landmark.
Oli Scarff/Getty Images Europe/Getty Images
If you're going to create one of London's most iconic buildings, you want to make it good enough to call home. Rogers Stirk Harbour + Partners set up shop on the 14th floor, and will be offering tours of their open-plan offices with views over the City and Canary Wharf.
Paul Gilham/Getty Images Europe/Getty Images
For the first time all 114.5 meters (1232 feet) of Anish Kapoor's red steel sculpture will be part of Open House London, complete with its newly opened and fully operational slide. Fun fact: The sculpture used enough steel to make 265 double-decker buses.
Courtesy Open House London
The new cancer center at Guy's Hospital cost £160 million ($212 million) to build, and makes the hospital the first in Europe to have above-ground radiation facilities.
Courtesy Open House London
The industrial-style building is part of the Royal College of Art's expanding South London campus, which unites the college's fine art and applied arts programs.
Courtesy Open House London
The Victorian subway once connected High Level Station to the Crystal Palace. The palace burned down in 1936 and station was demolished in 1961, but the subway, resembling a vaulted crypt, remains.
Dan Kitwood/Getty Images Europe/Getty Images
The $20-billion megaproject winding its way under central London is in its final stages, and stations at Bond Street, Canary Wharf, Custom House, Farringdon, Liverpool Street, Tottenham Court Road and Whitechapel will all get an advanced public preview.
Courtesy Open House London
Tin House, framing a private courtyard, is made up of interconnecting pavilions.
Courtesy Open House London
A 1960s mid-terrace near Finsbury Park has been revitalized by Archmongers with brick and timber extensions, glazed façade tiles and full-length windows.
Courtesy Open House London
Completed in 1972, the concrete council estate contains the aerial walkways popular at the time.
CNN  — 

Politics in Britain has, in recent months, looked something like a game of musical chairs. Careers have been made and broken, offices resigned from and assumed.

One man who’s profited from the tumult is former Mayor of London Boris Johnson – he’s walked from Norman Foster’s City Hall to the Italianate chambers of the Foreign and Commonwealth Office.

And now you can, too – if only for a weekend.

Snooper's paradise: A sneak peek inside London's most prestigious private homes

On September 17 and 18, Open House London gives the public a free pass to look around some of the city’s most exclusive locations – such as Johnson’s new digs – many of which are hidden behind lock and key for 363 days a year.

Read: The secrets behind Japan’s micro homes

Now in its 24th year, the event boasts a glut of new acquisitions. Of the 750 venues, 140 have never had such public access before. For instance, you can scale the Leadenhall Building (aka The Cheesegrater) designed by Richard Rogers, and visit Rogers’ House, which the British architect built for his parents in Wimbledon.

Five winners of the Stirling Prize – the UK’s most prestigious architectural accolade – are also on show, but it’s private homes, such as Folds by Bureau de Change Architects, in Haringey, that set pulses racing. It’s not often you get to look around a stranger’s living room or take a peek in their garden, especially not those as beautiful as this.

Courtesy Hogarth Architects
The Hidden House in Kensington features a light-up dance floor and waterfall.

Housing projects include self-built and zero-carbon homes, while Bedzed, in Sutton, and Walter Segal’s buildings, in Lewisham, show that there’s more than one way to skin a cat.

Yikes! London luxury tower crowned UK's worst building

If daylight isn’t your thing, you could always delve beneath the city into the labyrinth of Crossrail – a project with a budget in excess of $20 billion. (Have a look before it opens and the commuters descend.)

“From a Battle of Britain Bunker to the Argentine Ambassador’s residence, Open House weekend gives Londoners the chance to explore the city’s great buildings and places that are usually off-limits,” says Open House director Rory Olcayto.

“Whether its super-contemporary private homes, iconic skyscrapers or hidden gems like the Crystal Palace subway, very little is off limits during these two days.”

Read: Number of spiraled skyscrapers soars

There’s a lot of ground to cover, but if you don’t manage to visit Boris’ past and present haunts, you could always go one better than him: walk through the door of 10 Downing Street.

Open House London 2016 takes place on September 17 and 18.