See highlights from the 700 or so buildings taking part in London's Open House that you can still turn up at and see on the day. Plus a selection of buildings from other participating cities around the world, including Barcelona, which launches this year
Since it started in 1992, Open House London has grown from 200 buildings to 700 throwing open their doors to the public this weekend. While some of the highlights are reservation only - such as the BT Tower, which is participating for the first time this weekend - you can still turn up on the day and enjoy many of the city's architectural highlights, such as the Royal College of Physicians in NW1 abovePhotograph: PRSeen here at night, the Grade II-listed Royal College of Physicians is one of London's most important post-war buildings - with dramatic interior spaces and white mosaic exterior - designed by Sir Denys Lasdun in 1964. 11 St Andrew's Place, Regent's Park, NW1 4LE, Sat 11am-4pmPhotograph: PRForeign Office and India Office: These Grade I-listed Victorian government buildings include the magnificently decorated Durbar Court - the masterpiece created by Matthew Digby Wyatt from 1861-67 - in the Former India Office. King Charles Street, SW1A 2AH. Sat/Sun 10am-5pmPhotograph: Nick WoodfordLloyds of London: Home of Lloyd's international insurance market and one of the City's most celebrated buildings, designed by Sir Richard Rogers, this is - like his Pompidou Centre in Paris - a key example of British High-Tech architecture. A RIBA Award Winner with many sustainable features that were ahead of their time. One Lime Street, EC3M 7HA. Sat - 10am-5pm. First come basis, queuing if necessary. Last entry 4pmPhotograph: Anny Sun22 & 23 Bateman's Row: A new mixed-use building with office, gallery and residential units on one confined site designed by by Theis & Khan. There is a deliberate play of opposites throughout; rough and smooth, solid and void within a careful composition that develops from a dark base to an open-glazed top. RIBA Award Winner 2010. 22 & 23 Bateman's Row, EC2A 3HH. Sat - 10am-4pm. First come basis, queuing outside if necessaryPhotograph: Nick WoodfordRoyal College of Art Sackler Building, Painting Department: Housing studios, offices and workshops for the RCA's Painting Department, the old building - a single storey factory - has been transformed into a series of new day-lit spaces under a dramatic roof form by architects Haworth Tompkins. RIBA Award Winner 2010. 14-22 Howie Street, SW11 4AY. Sat/Sun 1pm-5pm. First come basis, queuing outside if necessaryPhotograph: Philipvile.comOpen House worldwide:Barcelona, a city famed for its vibrant and imaginative architecture, is the latest city to take part in Open House - along with Tel Aviv and Chicago - joining New York, Dublin and Galway in the Open House family. Running from 16-17 October, Barcelona highlights from 150 sites set out along 11 routes, will include residential buildings such as the Casas-Carbó modernist house at Paseo de Gracia, the evocative Torre del Rei Martí at Plaça del Rei and the Mercat de Santa Caterina, shown above. Full details on their websitePhotograph: PRMercat de Santa Caterina, Barcelona: this local market has been redeveloped with a huge, undulating canopy covering a former rundown neo-classical market in a large square within sight of the gothic Catedral de Barcelona. The canopy consists of a mosaic of 325,000 multicolored hexagonal Spanish tiles set in mortar, "whose various colors recall a sill life of produce." Photograph: Pepe NavarroBarcelona Biomedical Research Park: This building has a total surface of more than 55,000 m2 and is located on Barcelona's seafront. The building project has been carried out by two prestigious architects - Manel Brullet and Albert de Pineda - who have attempted to create a building that adopts the specific objectives of PRBBPhotograph: WijkmarkDublin's Open House runs from 7-10 Oct, and features city landmarks such as the 50,000-seater Aviva Stadium (the old Landsdowne Road rugby ground, above), the Eircom Building at Heuston South Quarter and historic buildings including Leinster House and the Casino in Marino. Pre-booked backstage tours will be led by the Aviva stadium architects Photograph: Donal Murphy PhotoOpen House New York (9-10 Oct) highlights include Staten Island’s Conference House, the only pre-Revolution manor house still standing, the first ever public tour of the newest and still closed section of The High Line and tours of Atlantic Avenue Tunnel, the world's oldest subway tunnel. Open House continues to spread to other global cities, with Rome currently in the pipeline. For up to date information visit openhouseworldwide.org/Photograph: Sean Hemmerle