The architect unveiled these proposals yesterday for a 600m-tall skyscraper in the heart of Moscow.
The 'mixed-use, super-dense, vertical city' will cater for 25,000 people according to the architect, which revealed the project at the MIPIM property fair in Cannes.
The structure, which will be the tallest naturally ventilated tower in the world if it is built, would be triple glazed from top to bottom.
Foster described 'Moscow City Tower' as 'three arms that meet at a central green spine running the full length of tower'.
A spokesperson said: 'Wider at the base and tapering towards the top, the pyramidal form is elegant and slender in profile.'
The tower, which would be located 6km from the city's Red Square, would cope with high wind loads using its sloped fan columns, which extend up the building.