For eleven months the CIA and MI6 listened to the Soviet army from a tunnel under East Berlin. Moscow knew before the digging started. The story, and what to visit.

West Berlin was not one island but an archipelago: a dozen detached scraps of territory surrounded by East Germany, from a village held by American helicopter to a meadow nobody could agree was there.

In 1972 West Germany finally recognised the state that built the Berlin Wall. The Basic Treaty did not remove one block of concrete, but it opened the border to millions of visitors while the Wall itself grew deadlier.

The East Side Gallery is a 1.3 km stretch of the Berlin Wall painted by 118 artists from 21 countries in 1990 – the world’s longest open-air gallery. The story behind its most famous murals, how it was nearly demolished, and how to visit it today.

The Berlin Wall did not appear out of nowhere. It was the last move in a four-year crisis that began on 27 November 1958, when Nikita Khrushchev gave the West six months to get out of Berlin – and which ended with American and Soviet tanks facing each other, guns loaded, at Checkpoint Charlie.

Eight years before the Berlin Wall, East German workers rose against their own government. On 17 June 1953 a strike on Stalinallee became a national revolt of a million people – and Soviet tanks crushed it in an afternoon. The story of June 17, why it failed, and where to find it in Berlin today.

For 28 years, crossing the Berlin Wall meant checkpoints, paperwork and the forced exchange of money – and for West Berliners, years when the gates were shut entirely. How the border crossings worked, the Passierscheinabkommen day-pass agreements, the Palace of Tears, and how to visit the crossing sites today.

East Germany’s Ministry for State Security ran the densest surveillance network in history – 91,000 officers, 170,000 informants, files on six million people. How the Stasi worked, how it fell, and how to visit the Stasi Museum and Hohenschoenhausen prison today.