16 September 2011
Last updated at 18:22
Westminster's Foreign Office & India Office is one of a number of government buildings throwing open their doors to the public this weekend, 17/18 September, as part of Open House London.
Nearly 800 properties, places and neighbourhoods feature in this annual celebration of the capital's best architecture, now in its 19th year.
They range from skyline icons, such as the BT Tower, to private homes, modern wonders and Victorian splendour.
Good design is the dominant theme but the event is also about the ongoing transformation of London. These narrowboats around a shared open space are providing solutions for living and working in the east of the city.
The LSE's recent transformation - by architect Nicholas Grimshaw - retains its original Beaux Arts facade but now includes a soaring central atrium with an art installation, a new lecture theatre and rooftop terrace.
Islington's Angel Building is another re-invention, this time of an early 1980s office block. A RIBA award winner, it features an energy-efficient glazed skin, an art piece in the foyer and a terrace offering London-wide views.
Hourly architect-led tours - of this three-storey new build in Hampstead, north London, for instance - are also part of Open House weekend along with neighbourhood walks, cycle tours, talks and debates.
This year's event also features nearly 50 projects with landscape at their heart, inviting visitors to see green improvements in Lewisham, at the 2012 Olympic Park and the award-winning Dalston Eastern Curve Garden, built on abandoned railway land with the help of apprentices from a nearby youth centre.