Downing Street's most famous resident, the black door of Number 10, sits behind iron gates that weren't always there. Children once posed for photos with that door, touching the very brass that prime ministers polished with their palms. Now armed police guard both ends of this curious cul-de-sac, built in the 1680s by Sir George Downing, whose career reads like a handbook for political survival.

Downing was a royal spy who spent years working against King Charles I, then nimbly switched sides when the monarchy returned, hunting down his former spy comrades with such enthusiasm that he earned both this patch of Westminster land and a portrait that supposedly still hangs in Number 10's entrance hall. The street he built has housed prime ministers for three centuries, though with over 100 rooms, the residence is worth about six million pounds, a quarter of what David Beckham's eight-bedroom London home commands.

VoiceMap's self-guided audio tours trace Downing's espionage legacy through Westminster's power corridors, reveal how Number 10 featured in James Bond's Skyfall, and explain the peculiar tradition of the red budget briefcase, paraded for photos like Paddington Bear's luggage.