Open House London Explained: How to Get In and What to Book First

Open House Festival is the official name, though almost everyone searches for Open House London. It is run by the architecture charity Open City and opens buildings and sites across all 33 boroughs, free of charge. The 2026 edition was the 35th. This guide uses that year as a template, because the pattern tends to repeat. Dates for the next festival are yet to be announced, so check Open City's visitor FAQ for the latest.

What it is, and what it costs

Everything in the festival is free to attend. Donations support Open City's work, but nothing is gated behind a payment. The programme is large: more than 600 listings at launch in 2026, including 143 places new to the festival, with some counts nearer 800 once activities were included.

The catch is not money but time. Free tickets for the popular buildings vanish quickly.

The timeline to expect

In 2026 the festival ran across two weekends in mid September, and the pattern in recent years has been a Saturday to Sunday span of about nine days. Dates moved a little each time, so do not assume the next ones.

• Mid July: the programme is published. Until then the website shows the previous year's listings, which is an easy way to get confused.
• Mid July to mid August: the ballot window for the one building that was balloted in 2026, 10 Downing Street.
• Midday on a Wednesday in late August: general booking opens.
• September: the festival itself.

Step one: make an account

You need a free Open House Festival visitor account to book tickets or add drop-ins to your itinerary. Accounts from earlier years, including volunteer accounts, still work, so check before creating a duplicate. Do this well ahead of booking day rather than at 11.59am.

Step two: understand the three ways in

Drop-in

Many places need no ticket and have no maximum number of attendees, though you may queue at busy times. The Architects' Journal said more than 500 buildings were drop-ins in 2026. Open City still recommends adding drop-ins to your itinerary, so organisers can contact you if something changes.

Booked tickets

Ticketed events have a fixed capacity and can fully book. Some buildings ask for the names and emails of every visitor in advance. For Lloyd's Building, details were due by 5pm on the Monday before the festival, and under-16s needed an adult with them.

The ballot

Ballots are for the rarest tickets. In 2024 there were ballots for 10 Downing Street, BT Tower, BBC Broadcasting House, the then future London Museum, Trellick Tower and Morden College almshouses, and the first four drew over 30,000 entries. In 2026 only Downing Street was balloted, with entries open from mid July until midday on a Monday in mid August. If the rules from 2025 repeat, you can enter once per time slot but for as many slots as you like, you must be logged in first, winners are told the afternoon after the ballot closes, and a plus-one can be nominated. Check the current rules before relying on that.

Booking day tactics

ianVisits advised logging in before midday, because the site can struggle under demand. Reader comments on its article described a slow site at 12:00 and ticketed buildings looking fully booked almost immediately, one saying within 20 minutes. Those are anecdotes rather than official figures, but they fit the advice: be logged in, know your shortlist, and have a second choice for each slot.

There is no official filter for buildings that need booking, according to ianVisits, which compiled its own list. Londonist noted a new for 2026 filter in the all listings dropdown, and the programme calendar has a facilities filter for accessibility information.

The buildings that fill up first

These were the 2026 examples. Treat them as a guide to what tends to go fast, not a promise of what will return.

• BT Tower: the most in-demand ticket in most years, normally ballot only but general booking for the second weekend in 2026. London x London said it is being converted into a hotel due to open in 2029, so 2026 may have been a last chance.
• 10 Downing Street: ballot only.
• Lloyd's Building: Richard Rogers' design, marking its 40th anniversary in 2026, with advance booking required.
• Mansion House: the state rooms tour needed booking.
• Lambeth Palace Library, Hoxton Hall, Crystal Palace Subway, National Theatre Studio, Gensler's 6 Moretown and Boston Manor House: all on ianVisits's list of places needing advance booking.
• Union Chapel: self-guided access was free, but ticketed events needed pre-booking.

The Architects' Journal reported that tickets for Lloyd's, 22 Parkside, BT Tower and Downing Street had already been awarded by registration or ballot before the festival began.

The drop-in fallback

If the ticketed buildings slip away, the drop-ins are far from a consolation prize. Cultural Wednesday's advice is to pick an area with several open buildings and move to whichever queue is shortest. It listed the Royal Society, Burlington House, the Argentine Ambassador's Residence, the Romanian Cultural Institute and Two Temple Place among its drop-in picks. The Architects' Journal pointed to Lillington Gardens Estate, Tooting's former Granada, now Buzz Bingo, Bruno Court at the German Hospital, Foster + Partners' Riverside HQ, Herne Hill Velodrome and the Quentin Blake Centre. Lloyd's Register Building at 71 Fenchurch Street offered self-guided entry from 10am to 4pm, last entry 3.45pm, and was step-free.

Londonist's best new picks were a good reminder that fresh listings can be less crowded: West Ham Pumping Station, Ongéan in Herne Hill, St George the Martyr in Bloomsbury and the Carbonic gas works on Lea Bridge Road.

Curated neighbourhood clusters help too. In 2026 the London Society highlighted Bankside, Fitzrovia and Piccadilly and Jermyn Street, each with several openings within walking distance.

A sensible plan for next year

• Check open-city.org.uk for dates, which are yet to be announced.
• Create or test your visitor account in advance.
• Diary the programme launch, then the ballot deadline, then booking day.
• Pick two ticketed targets per day and a cluster of drop-ins nearby.
• Add drop-ins to your itinerary so you hear about changes.

Done that way, a free festival with a famously harsh booking scramble becomes manageable, and the queue at a good drop-in is a perfectly decent way to spend a September morning.