Heathrow's Terminal 5 feels more like a stadium or amphitheatre than an airport.
By Victoria Bone
At 400m long, 160m wide and 43m high it is enormous - as big as 50 football pitches across its five floors - and it has the largest span roof in the UK.
It is also surprisingly pleasant - for now at least - although an estimated 30m passengers-a-year will test that functional beauty to the limit.
With six months to go until the 27 March opening, the construction work is done and T5 is ready to be fitted out with shops, seating and so on.
It is also entering the crucial stage of "proving trials" - in layman's terms, checking everything works.
Top of the list - and of air travellers' gripes - is the baggage system, and its 18km of track are running 24 hours-a-day checking for glitches.
Security officer Mick Pearman, who gave the BBC News website a tour, explains: "We've got cases and bags just like normal but without passengers.
Automatic check-in desks will print out tickets bought online
"They're all labelled with flight numbers and we put them through the system to make sure they all end up where they're supposed to.
"They're all different weights as well and some are actually overloaded so we can check the system copes when it's pushed to its limits."
Mr Pearman has worked on T5 for eight years and is immensely proud of what has been achieved, especially given the safety record.
On 10 occasions, T5 has surpassed one million man hours without a reportable accident.
Experts predicted five or six fatalities on a project of this scale - there has been one.
T5 will have shops, cafes and bars like any other airport, and some of those are already fitted out - Harrods to name one.
The terminal also has some new features, particularly in the area of security.
All passengers on domestic routes will have their photograph taken and fingerprint scanned at passport control. Their fingerprint will be checked again at the gate before boarding.
Heathrow's operator BAA says this was to allow them to "enter and use the full departure lounge and facilities".
"It's also so we can make sure that the person who turns up at the gate is the same one who checked in," Mr Pearman adds.
Another state-of-the-art addition involves X-ray scanners which screen hand luggage before they enter departures.
Never used before, the Advanced Threat Identification system is designed to detect explosives and liquids in baggage and automatically divert suspicious bags to one side for further examination.
In fact, the entire building is designed with security in mind: "We've been able to work security in, rather than try to add it on afterwards," Mr Pearman says.
As well as the technology, T5 feels different from the Heathrow we know.
It is much more open-plan with large glass walls, and resembles new rival Stansted more than its older siblings 1, 2, 3 and 4.
Mr Pearman says: "From the word 'Go' we wanted lots of daylight. We also have ambient lighting that goes up or down depending on how dark it is outside and there's lots of glass to reflect light."
The baggage reclaim area is huge and bright, with double-decker bus-sized screens which will display carousel information.
The view for passengers once they get through arrivals is equally grand. A huge glass wall with fully-grown trees behind gives a feeling of stepping straight outside.
Making the terminal "green" extends further too.
"The trees are London Planes and they absorb pollution," Mr Pearman says. "And we collect rainwater off the roof and reuse it for things like irrigation."
Recycled glass and aggregate have also been used in the build and a combined heat and power plant on site will provide 85% of T5's energy cleanly and efficiently.
Security operations manager Bob Smalley says: "For everything you see above ground, and that's a lot, there's the same again below ground.
"People don't realise what's beneath the surface and behind the scenes - that's why it's taken five years."
T5 has its own brand new air traffic control tower, built because the old one didn't have a good enough view.
There is also currently one satellite building, T5B, which together with the main terminal provides more than 60 gates.
By 2011, T5C will be built and will also be served by the rapid transit system which delivers passengers to their gates.
Stephen Nelson, chief executive of BAA, says: "People have worked here for five years or more and are deeply proud of it. In that way, it's a people story as well as a physical story."
And Mr Nelson says T5 is just the first in a series of upgrades to Heathrow, including refurbishment of terminals 3 and 4 to bring them up to scratch.
"By 2012, the majority of people will travel through parts of the airport that don't exist now," he adds.