
Crazy hypothetical scenario! London airport in a parallel universe.
If money and construction space were no object, and all six of London's major airports disappeared, leaving only one to be built on stilts (similar to Madeira Airport) directly above Euston, St. Pancras and King's cross stations (purely for the sake of calculating easy mass transit access), how big could that airport be (in terms of runways, number of terminals, cargo warehouses, concourses, and boarding gates), and how many millions of passengers per year could it handle? It’s a matter of genuine curiosity for me, after discovering that Dubai plans to build the world's largest airport, capable of handling up to 260 million passengers a year.