It's the capital's largest annual festival of architecture and design, now in its 23rd year: a city-wide celebration of the buildings, places, and neighbourhoods where we live and work.

The Open House London event is fully inclusive and admission is free for all Open House London events each September. You will need to find out which buildings are opening / walks and talks planned in order to plan your visits. To pre-order a copy of the programme for this year's event, click here

The dates for Open House London in 2015 are 19 & 20 September. The online search tool will be available in mid-August 2015. 

The Open House London will feature 850+ sites, and at many of them there will be someone to show you around and answer your questions. These are the Open House guides and stewards, and there are thousands of them – some professional, some amateur enthusiast, all volunteering their time and knowledge. In recognition of their role their badge enables them to gain priority access to buildings apart from those that are pre-booking only. 

Look out for the entries coded as having architects on site; it means that architects will be giving talks and tours of some of the buildings they’ve designed. There were a staggering 1600 tours being given by architects last year in total. Sometimes you will also find the practice director on site. Also, some of their studios/offices will be open, so that you can see the projects they’re working on. Don’t forget to look out for the factsheets too which will be available at most buildings. Entry to a few of the properties will require you to book in advance. Relevant contact details will be given for you to do this.

Before the programme becomes available online you can order The Open House London from the shop page. The guide is also available to buy from selected retailers including bookshops and the RIBA and AA as well as museums and galleries such as the RA, Serpentine, V&A and the Museum of London. it is also available from bookstores such as the London Review Bookshop and Foyles. You can also download the Open House app here.