European Central Bank.

This guide to the European Central Bank in Frankfurt starts with the seven-centimeter concrete roof of the old market hall tucked inside the glass towers, built by architect Martin Elsaesser between 1926 and 1928 to feed the city. It follows that hall through October 1941, when the Gestapo rented the cellar beneath it and mass deportations began leaving from a rail spur on the spot, and through the market's ordinary trading years afterward until it closed for good in 2004. A memorial etched with survivors' own words now runs along the tracks outside.