For those of you who missed it, last weekend was Open House London 2014, which offered a chance to see inside 800 buildings across the capital that are not normally open to the public.
The most popular options this year included: The Gherkin, The Cheesegrater, The Bank of England, 55 Broadway (London Underground HQ), Houses of Parliament, and 10 Downing Street, among others. As you'd expect, they were incredibly busy, which meant you either needed to get a ticket well in advance, or be prepared to queue for hours.
However, there's a whole world of interesting building to explore besides the most popular ones. Better yet, you can often see two or three of them in the time it would take you to see one of the others.
Just to give you an idea of the types of buildings you can get access to, here is summary from what I managed to see this year: