Architecture: Mind the gap, in a robust and lyrical way

Norman Foster's new Canary Wharf station is a masterpiece of functional elegance.

London's newest and largest landmark is up and running. From today, the Jubilee Line Extension is open from Bermondsey to Canary Wharf, and within a few weeks the link to Waterloo will be made. The Canary Wharf station has actually been ready for months, but safety inspectors have been checking every millimetre of the line.

Docklands commuters will find not just an efficient service but an awe- inspiring station by Norman Foster. At 300 by 35 metres, the station is as long as Canary Wharf Tower - Britain's tallest building - which is high above it. Yet all that can be seen from over ground are three dramatic curved steel and glass canopies. They are more than shelters from the wind and rain: the elliptical glass canopies act as lanterns to beam as much light as possible deep into the station below.

Master builders in the Middle Ages used to put all their aspirations into creating crenellated cathedrals, their soaring spires designed to get worshippers below to look up to the heavens. This station is a cathedral in its awesome proportions - a cathedral for the secular age. Within its cavernous space, the smoothly sculpted concrete wings of the roofline, high overhead, provide shelter at the same time as they give the space lift-off. These wings are pinioned on incredibly tall and challengingly thin elliptical columns.

These reinforced concrete columns stretch 30 metres from platform level to the roof, where elliptical bearings allow the station to move in response to geological pressures. Since it lies below the waterline in the old West India Dry Dock, it was clear that the station needed to be weighed down from above if it was not to pop up like a cork. Nothing in the building has been staged simply for effect: everything has been done for load-bearing, mechanical-engineering or acoustic reasons.

No combustible materials are allowed in underground stations, so rather than use expensive stone, mosaic or marble, Foster left the utilitarian concrete, cast on site into columns and the butterfly wings of the roof, exposed. At the base where it can be touched, the concrete is clad in stainless steel to prevent vandalism and other damage.

Pre-cast concrete paviours cover the floor, while the barriers and all other surfaces in the ticket offices are stainless steel, aluminium or glass. At platform level, the concrete diaphragm wall cast into the ground is left exposed. Robust engineering informs the design, but the lyricism of the form transcends it. "This station is bold, it's magnificent," says Roland Paoletti, the man who commissioned it. "If Canada Water [which opened three weeks ago] is like the Fiat Punto - a remarkable, serviceable, stylish little car - this station by Norman is the Ferrari."

Norman Foster, who greatly admires Brunel, proves how close he is to the nuts and bolts of structures and how seamlessly he can hide such things as sprinklers, hoses and hydrants or tone them down without camouflage.

All cabling is housed under the platforms or behind walls, accessible via maintenance gangways so that the entire station can be serviced behind scenes. Peak-time traffic will initially be 40,000, but Canary Wharf station is built to take 100,000 - traffic will increase, especially once the tower blocks at Heron Quay are completed.

David Nelson, one of the partners and the architect who Roland Paoletti said he enjoyed working with the most, admits that they had a brilliant site. "Along with Will Alsop at North Greenwich, we were the lucky ones because we had no historic buildings above us, or anything too close to the footprint," he said.

This freedom has allowed the creation of two masterpieces along the scenic route of stations that is the Jubilee Line Extension.