Open House London 2026: 15 Buildings and Tours You Shouldn't Miss

My first Open House was back in 2015: the Foreign and Commonwealth Office on Whitehall, with a friend who talked me into it. The following year I went back for London's City Hall down by Tower Bridge, and I've been hooked ever since. For nine days every September, more than 800 buildings, tours and walking routes across all 33 London boroughs throw their doors open for free, run by the charity Open City, and this year is its 35th edition.

Open House London 2026 runs from Saturday 12 to Sunday 20 September, and if you've never done it, or you did it once years ago and forgot, here's my honest, opinionated pick of what's worth your time this year.

What Open House London 2026 actually involves

The format has changed a lot since the single chaotic weekend I remember from years back. It's now a full nine-day programme, which genuinely changes how you plan it: instead of cramming everything into one Sunday, a lot of buildings now offer multiple access dates spread across the whole festival.

Most things are drop-in, meaning you just turn up during the published hours and queue if you need to. The popular ones, especially anything resembling a skyscraper, a government building or a hidden underground space, need advance booking, and bookings for this year's ticketed slots opened back on 19 August. If you haven't booked by now, don't despair; some buildings release extra slots or run day-of ballots, and the drop-in list alone is bigger than anyone could see in nine days anyway.

Entry to literally everything is free. That's the whole point of Open City's charity model, and it's worth remembering when you're standing in a building that would normally cost £30 to tour.

If you want a preview of what this actually feels like, I've covered two Open House visits before: a diary from Inside 113 Chancery Lane, and a look at the Nash terrace that is Inside the British Academy — both are exactly the kind of unglamorous magic this festival specialises in.

If you like tracking how the festival changes year to year, I've done full write-ups before too: a 2022 look at London's most iconic buildings and a 2023 architectural marvels shortlist.

The icons you'll finally get to see from the inside

Some buildings on the list don't need an introduction, they need an excuse, and Open House is that excuse. The Lloyd's Building is turning 40 this year, and Richard Rogers' famous inside-out design, with its lifts, ducts and stairwells all worn on the outside like a mechanical exoskeleton, is opening up so you can finally see the guts of the thing from within, including a ride in one of the glass lifts that were the first of their kind in the UK when it opened in 1986.

The BT Tower is doing something similarly rare: tours up to the 34th floor, where a revolving restaurant used to spin high above the city before it was closed to the public for security reasons. The floor still turns, and Open House visitors get to ride the high-speed lifts and stand where that restaurant used to circle, with a panoramic view that's normally reserved for BT staff. Given the tower is due to become a hotel with construction starting in a few years' time, this might be one of the last chances to see it while it's still recognisably itself.

A short walk from the BT Tower is Senate House, the Art Deco tower in the middle of Bloomsbury with a starring role in dystopian fiction folklore. I've written a full dive into what's inside its library before, if you want the details.

Then there's the trio that always gets people booking accounts they'll only ever use once a year: No 10 Downing Street, BBC Broadcasting House and Mansion House, the Lord Mayor's official residence. All three appear in this year's programme, and all three are the kind of building most Londoners walk past their whole lives without ever seeing the inside of.

Bookable tours worth setting an alarm for

A few of this year's best experiences need a ticket, and they're the ones I'd prioritise booking first if slots are still available, because they genuinely sell out. The Great Eastern Hotel, now the Andaz London by Liverpool Street, was designed in 1884 by Charles Barry Jr, and its Open House tour goes behind the scenes of the hotel to a Masonic Temple hidden inside the building that most guests have no idea exists. It's a guided tour, limited availability, and not wheelchair accessible, so plan accordingly.

Two Temple Place is the other one I'd chase. It's William Waldorf Astor's extraordinary 1895 neo-Gothic mansion on the Embankment, and the interior includes a staircase carved with characters from The Three Musketeers, which is exactly the kind of unhinged Victorian detail that makes this festival worth doing every year.

Lincoln's Inn, one of London's four ancient Inns of Court with records dating back to 1422, is the third: an 11-acre site holding a Grade I-listed Old Hall, a Grade II-listed Great Hall, a chapel, one of the UK's most important law libraries, and six centuries of London's legal history behind walls most of us never get past.

Free drop-ins and proper hidden gems

My favourite category of Open House find is the building you'd never have gone looking for. The House Mill in Bromley-by-Bow is the world's largest surviving tidal mill, an oddly thrilling fact to say out loud, tucked a short walk from Bromley-by-Bow tube station and close to the Olympic Park. It's running drop-in open days and guided tours across the festival.

The Moravian Church and graveyard in Chelsea is a total hidden gem, tucked just off the King's Road on the site of Thomas More's old house, Beaufort House. It's the sort of place you could live in the neighbourhood for years and never clock.

For something with a sharper edge, the Karl Marx Memorial Library occupies a building originally constructed as a Welsh school in 1738, and now holds around 50,000 books along with rare periodicals and pamphlets. And Guildhall, the ceremonial heart of the City of London, is the oldest secular building in the Square Mile, with stonework dating back to at least 1440. Both are free, both need nothing more than showing up.

If reading rooms and dome ceilings are your thing generally, not just for one weekend a year, I've also written about the Gothic archive-turned-reading-room inside the Maughan Library at King's College, easily one of my favourite interiors in the city.

For the architecture and archive obsessives

If you're the type who reads building credits at the end of a documentary, a few entries in this year's programme are aimed squarely at you. The Zaha Hadid Foundation archive is appearing in the Open House programme for the first time, offering rare access to her architectural drawings, models and personal items, a genuinely unusual chance given how tightly her archive is normally held.

Billingsgate Roman House and Baths is one of Roman London's more fascinating remains, hidden in the basement of an ordinary-looking office block, with guided tours across two of the festival's Saturdays.

How I'd actually plan the nine days

With this much choice, planning by neighbourhood beats planning by building. This year's curated festival areas include Bankside, Fitzrovia and Piccadilly & Jermyn Street, plus clusters across a growing number of boroughs, so picking one patch of the city and working through everything nearby saves you from crossing London twice in a day for two buildings that were five minutes apart.

Weekday visits, especially Tuesday to Thursday, are noticeably quieter than the weekends bookending the festival, so if your schedule allows it, save the big weekend crowds for neighbourhood wandering rather than queuing for a single popular building. And if you missed the 19 August booking window for a ticketed favourite, it's still worth checking the programme site directly closer to the date; cancellations and extra slots do appear, and the free drop-in list is generous enough to fill nine days on its own.

If this kind of once-a-year access is your thing, keep London Open Gardens on your radar too; it does the same trick every spring, but with private gardens instead of buildings.

Getting around without wasting half your day on the Tube

The Underground and bus network are still the most practical way to move between venues, but Open House is one of the few times of year I'd genuinely recommend walking further than feels necessary, because the buildings themselves are half the reason to be on foot in the first place.

September in London tends to bring mild days, averaging somewhere around 19-20°C, so a jacket for the evening and comfortable shoes for the queuing is about all the planning your outfit needs. Bring a phone charger; you will absolutely end up looking things up on the programme site mid-walk, discovering a building two streets away you hadn't clocked, and rerouting your whole afternoon.

A free account on the Open City site is required for any of the ticketed bookings, so if you haven't set one up yet, do it before you're standing outside a building refreshing the page. And if you're new to this and slightly overwhelmed by the scale of it, that's completely normal; even people who do this every year still discover something new, and the festival's own website has a filter for 'new for 2026' listings if you want to skip the buildings you've already ticked off in previous years.

Visiting Open House London 2026

Dates: Saturday 12 to Sunday 20 September 2026.

Cost: free, always.

Booking: most buildings are drop-in with no ticket needed; a handful of the most popular tours require advance booking, which opened at midday on 19 August, though it's worth checking closer to your visit for late-released slots.

Getting there: pick a neighbourhood cluster, use the Tube and buses between clusters, and walk within them.

Best time to go: weekdays, especially Tuesday to Thursday, if you want smaller queues; weekends if you want the full atmosphere and don't mind waiting.

However you spend your nine days, the whole point of Open House is the same feeling I had wandering round the Foreign and Commonwealth Office back in 2015: London hands you back a building you thought you already knew, and it turns out you'd never actually seen it at all.

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