Should you rise from the underground, step off a train from Cambridge, or pass en route from Paris to Edinburgh next week, have the decency to gaze up at the reincarnated London's King's Cross station. After five years of construction the new western concourse is all but complete: a smaller but equally elegant counterpoint to its neighbour, St Pancras International.
has restored and preserved Victorian facades but added a stunning modern roof, creating an uninterrupted space springing from one plume of white steel - and all without, as the company stresses, cancelling one train.
The wow factor in the £500m redevelopment is a "diagrid" roof - the kind seen atop the British Museum's Great Court, but in this case spanning 150m with not one visible bolt in the entire structure. Designed to cover the largest area without the need for supporting columns in the middle, this vast bright space is "the head of a matchstick", the engineers explain. The steel piles underpinning the visible lattice are driven 50m into the ground.
Architect Hiro Aso, who has been part of the project with architects John McAslan since submitting their winning design in the late 1990s, says: "It leaps, it's glorious, organic - a very bold expression of the overlay of new and old. We could have been a bit more apologetic, or subordinate, but this is an absolutely amazing structure."
After the cramped conditions that have faced the 47 million passengers who use the station each year, the revamp promises not only free flow but perhaps even time to relax. An elevated second storey in the concourse will have cafes and shops more detached from the commuter rush. The biggest pub of any railway station will also now be found here: a boon for many awaiting the evening East Coast services, if not perhaps the cleaning staff or guards.
Although wooden passages of construction hoardings have funnelled passengers through to the western platforms and St Pancras for years, many were utterly oblivious of the transformation taking place behind the boards, according to project manager Ian Fry. "We've held presentations for people here showing what we're doing, and they frequently ask: 'So when are you going to start?'"
Clearer light has already been falling on the eastern platforms, the main train shed, since the first sections of its glass roof were recently completed.
Photovoltaic panels will generate 10-20% of the station's power needs. That work continues, and after the Olympics builders will start pulling off the scabrous eyesore, the "dingy green canopy" (as Network Rail's own literature describes it) that hangs over the present entrance. For a few last days the ageing concourse behind, remains the main point of departure. Next year it will be demolished to make way for an outdoor plaza.
The most frequently asked question, Network Rail bosses admit, is the location of platform nine and three-quarters, boarding point for the Hogwart's Express of Harry Potter fame. Despite the station's reconstruction the monument, a luggage trolley vanishing into the brickwork, has kept tourists queuing - even when relocated to a dismal exterior wall on the accident blackspot of York Way junction, a setting to challenge the most ardent JK Rowling fan's suspension of disbelief.
A new space will be found amid the renovation of the original 1852 building - but discreetly, not between platforms nine and 10, and facing away from any trains lest the incessant flash photography unsights the drivers.