Open House weekend is when buildings in London throw open their doors, free of charge, providing access to little known interiors or hosting special events that interpret the capital's architecture, old and new, in a new light.

Please note that different properties open on different days and at different times during this weekend-long event. Be sure to check individual listings on the Open House website, as all sites will have different booking procedures.

This year's participants include:

Alexander Fleming Laboratory Museum 

Visit Alexander Fleming's laboratory, restored to its 1928 condition, and explore the story of Fleming and the discovery and development of penicillin through displays and video.

Saturday, 18 September: Tour at 4:00
Sunday, 19 September: Tours at 1:00, 2:00 and 3:00

Pre-book ONLY on 020 3312 6528 or email Kevin.Brown@imperial.nhs.uk. Maximum 20 per tour.

Benjamin Franklin House will be open from 10.30-4pm on both Saturday 18 and Sunday 19 September with tours running every half hour. Visitors will need to pre-book these tours through Open House in advance.

The Royal College of Physicians will be offering CP is holding its own College Open Day, along with participating in Open House.

On offer will be architectural tours looking at Sir Denys Lasdun’s Grade I listed building, and historical tours focussing on the college’s history and collections. There will also be chocolate workshops, tastings and talks, celebrating Sir Hans Sloane’s 350th anniversary.

Saturday, 18 September: 11am-4pm.

Visit the headquarters of the Wellcome Trust, located adjacent to the Wellcome Collection and Wellcome Library at 215 Euston Road. The building was designed by Hopkins Architects and opened in 2004. Architect-led tours of the building, children's activities and talks on the Thomas Heatherwick sculpture 'Bleigiessen' will be offered on Saturday, 18 September.