Day 2 · Speicherstadt and Miniatur Wunderland
The whole morning in the Speicherstadt, the world's largest warehouse district (UNESCO World Heritage). Book ahead for Miniatur Wunderland: 2-3 hours minimum. Afternoon in HafenCity: contemporary architecture, Marco Polo Terrassen, coffee by the water.
Day 3 · Reeperbahn, St. Pauli and night
Quiet morning in Schanzenviertel (cafés, bookshops). Visit Beatles-Platz and the Old Elbtunnel (free, open 24 h, a 1911 pedestrian tunnel under the Elbe lined with ceramic tiles). Night in the Reeperbahn: jazz in any basement, an Astra beer in your hand.