Fort X

This guide to Fort X in Cologne opens with a question: why is a teenager skateboarding through a dry moat where Prussian riflemen once stood guard? It traces the fortress back to its construction between 1819 and 1825 under military engineer Ernst Ludwig von Aster, one of eleven forts ringing the city's left bank, and follows what happened after the First World War, when the Treaty of Versailles ordered it torn down and Cologne residents pushed back. You'll hear how garden director Fritz Encke and a young mayor named Konrad Adenauer answered that order, and what the fort's cellars were used for once the Second World War arrived. Wander the old ramparts at your own pace.