[1][2] Part of the Parliamentary Estate, the building augments limited space in the Palace of Westminster and surroundings.

The architects, Michael Hopkins and Partners, published their design in 1993 and the existing buildings on the site were demolished in 1994.

The building is named after the chained portcullis used to symbolize the Houses of Parliament on letterheads and official documents.

A thick slab of concrete separates Portcullis House from the station, reportedly to defend against any underground bomb attacks.

The design life of 120 years meant that aluminium bronze was chosen for exposed metal on the roof and walls.

These Committee rooms are accessible to the public and are fitted with television cameras and microphones, to broadcast the proceedings via BBC Parliament and via parliamentlive.tv.

On the ground floor are a range of services including a waiter-service restaurant ("The Adjournment"), informal cafeteria ("The Debate") and a coffee shop ("The Despatch Box"), available only to pass holders and their guests.

There is also a post office and an e-library, an enquiry point where Members and staff can use networked computers, run by the House of Commons Library.

Costs included £150,000 for decorative fig trees, £2m for electric blinds and, for each MP, a reclining chair at £440.