Willis Building is full up

Mitsui, the Japanese conglomerate, has taken the last available space at the Lord Foster-designed Willis Building development (above), the latest introduction to the City of London's skyline.

Willis, the insurance broker, unveiled its 28-storey headquarters on Tuesday. Adjoined to the development is a nine-floor building to be sub-let to Mitsui and Kennedys, the law firm.

British Land, the developer, built the second office block as it made better use of the available space. "British Land initiated the development because it was felt that Willis would get a better [financial] package by taking the whole site," said Greg Cooke, chairman of Atisreal UK, the scheme's property adviser.

Kennedys and Mitsui are due to move in this summer and are thought to be paying £50 per sq ft. British Land is in talks to sell the building to the Quwait Investment Authority for up to £400m.