If you want an indication of the level of interest in high quality architecture and design, look no further than Open House London. In the twenty years since the first event was held, tens of thousands of people have passed through some of the capital's hidden architectural gems, including spaces that are usually off-limits.

Open House London 2012 marks the 20th anniversary, and to celebrate we've come up with 20 destinations drawn from the list of over 750 places to see over the weekend of 22/23 September. This year there's also a special focus on infrastructure, green design, landscape architecture and numerous satellite events, with full details available on the Open House London website, openhouselondon.org.uk