This video shows how a new three-runway Heathrow would look, after a designer for the airport's potential expansion was chosen.
The architectural practice Grimshaw fought off competition from the likes of Zaha Hadid, who designed the aquatics centre for the London Olympics, to be appointed "concept designer" for an extended Heathrow.
Its winning vision for Heathrow's new Central Terminal Area features a sweeping skylight pouring natural light onto a plain, monochrome interior with a curved shop-lined balcony.
The airport, which is competing with Gatwick for the go-ahead to build a new runway, says the decision sends a "clear signal" to the government that it is ready to push ahead should it be chosen.
It praised Grimshaw's "visionary" concept designs, which it says "pushed the boundary of what an airport could be" and did so in a sustainable and affordable way.
Heathrow's head of design Barry Weekes said: "We look forward to working with Grimshaw to develop their bold ideas so that once the government approves the Heathrow expansion, we can create a world-class sustainable hub airport which delivers for our passengers, our airlines and also helps to integrate Heathrow with our local communities.
"With the Concept Architect and Programme Client Partners now in place, we are now ready to begin the process of expansion once the Government makes the right choice for the whole of Britain."
Grimshaw was founded in the UK by Sir Nicholas Grimshaw. Its previous projects include the Eden Project in Cornwall, the Grand Stand at Lord's cricket ground and the No 1 Court at Wimbledon.
Heathrow is now second favourite with some bookies to get the extra runway, with one bookmaker offering odds of 4/7 on for Gatwick to get the go-ahead.
Then transport secretary Patrick McLoughlin said following the EU referendum that there was unlikely to be any announcement before October.
But there has been speculation that new prime minister Theresa May, whose cabinet features several MPs opposed to Heathrow expansion , might make a decision sooner.