London Open House Festival: The landmarks taking part this year you should book to see now

The biggest architectural celebration of its kind in the world, London’s Open House Festival gives the capital’s keenest — and nosiest — design fans a chance to snoop around famous landmarks and the city’s most spectacular private homes.

Last year’s edition welcomed 375,000 visitors to 830 open days and events across all 33 London boroughs. This year’s event, which runs from September 12 to 20, is shaping up to be even bigger and better.

London Open House Festival Anna-Rose McChesney Think of the programme as split into three types of visit: balloted entry, bookable slots and drop-in visits. All are free, but you’ll need to be quick if you’re going to bag a ticket to some of the headline events. Last year most slots were snapped up in 20 minutes, according to festival organisers.

Bookings opened at 12pm on August 19 this year. Here’s what you need to know.

Create an Open House visitor account online now to enter the ballot for a guided tour from 11.30am to 1pm on September 13. Winners will be contacted shortly after the draw at midday on August 17.

While the majority of events are open to drop-in visitors, some of the landmark open days or tours are ticketed because they have a maximum capacity. So it’s first come, first served on Wednesday, August 19 when bookings open.

The iconic Lloyd’s of London building in Lime Street in the City is taking part in this year’s Open House Festival as part of its own 40th anniversary celebrations. Designed by British architect Lord Rogers and opened by Queen Elizabeth II in 1986, the specialist insurance and reinsurance marketplace was awarded a Grade I listing in 2011.

Lloyd's of London Jason Alden/Lloyds It’s known as the “inside-out” building, because Lord Rogers’ design placed the staircases, loos, glass lifts and pipes on the outside, leaving space for a spectacular central atrium that rises 60 metres to a steel and glass barrel-vaulted roof. Tours are taking place at various times on September 19.

A tour of Leadenhall Market may not sound the most impressive booking, until you discover that guided walks on September 19 and 20 include an exclusive visit to the Roman ruins beneath. Situated in Gracechurch Street, in the heart of the Square Mile and the centre of what was Roman London, it was originally a market for meat, poultry and game. Underneath lie the remains of a forum (market) and basilica (courts), which aren’t usually open to the public.

In previous years, entry to the BT Tower in Fitzrovia and BBC Broadcasting House in Marylebone was by ballot only, whereas this year the landmarks are available to book. Take a trip to the BT Tower’s famous revolving floor (158m high) at various times on September 19 and 20, or have a guided walking tour of the BBC’s Art Deco-fronted headquarters on September 19.

BBC Broadcasting House Jeff Overs In another rare chance to see inside a London landmark, the Wapping Hydraulic Power Station is open for tours on September 19 and 20. Built in 1890, it was the last hydraulic power station in London to be decommissioned, in 1977, and has been closed for the past decade.