Wannsee is two walks in one mood: a summer-Berlin idyll of lake, sand, and a folly-island — and, on the same shore, the villa where the Holocaust was administered. Hold both. The walk doesn't choose between them, and neither should you.
Start at the Strandbad Wannsee, the great 1920s lido built to give the city a beach. Walk the boardwalk for the Weimar architecture, not the sand. South along the shore comes the Liebermann-Villa — the painter's house and the garden he painted until he was driven out — and then, a few minutes on, the House of the Wannsee Conference. It is free, it is sobering, and it deserves your time; on 20 January 1942 the machinery of the genocide was coordinated in its dining room.
From there the mood lifts on the water. Pick up the shore path west to the ferry at Nikolskoer Weg and cross to Pfaueninsel — Peacock Island, a UNESCO garden with a white toy-castle, lawns like brushstrokes, and the birds underfoot. No cars ever reached it. Loop it slowly, take the last ferry back, and the S-Bahn home from Wannsee.
