This on tonight, 10.40pm BBC1:
Here's a sight you don't see every day: Alan Yentob donning a gorilla suit to guide us round the Empire State Building. And that's not even the strangest part of this film about skyscrapers. One archive clip is even more bizarre, showing as it does the leading American architects of 1931 gathered for a party dressed as their own buildings. The programme has some fascinating stretches, such as a trip to see the massive lift machinery of the Woolworth building, still working beautifully 93 years after it was installed. But there's the odd longueur, too, perhaps as a result of spreading the story over three films (the second is next Wednesday). Even so, anyone who loves great buildings will be enthralled.