Unter den Linden is the boulevard the kings built to be seen on, and the walk down it is a walk through everything Berlin has had to reckon with since. Two and a half kilometres, gate to island, with three of the city's hardest memorials set quietly along the way.
Start at the Brandenburger Tor with your back to it, facing east, so the avenue opens ahead. Drop south first to the Memorial to the Murdered Jews of Europe — walk into the field of stelae, where the ground falls and the blocks rise and the traffic disappears. Back on the boulevard, the linden trees take you past Bebelplatz, where a glass plate in the cobbles looks down on Micha Ullman's room of empty shelves, the 1933 book burning made permanent.
The Humboldt-Universität book tables come next, then the Neue Wache — one bare room, one Kollwitz Pietà, open to the sky. End where Unter den Linden ends, at the Lustgarten in front of the cathedral, with Museum Island and the U5 waiting.
