Four days lets Hamburg breathe. You get the harbour and the Speicherstadt, the old centre, the Alster and the Kontorhausviertel, a full day in St Pauli and Ottensen, and a fourth day for the museums, the parks and whatever the weather ruined earlier, which in this city is a real consideration. Base yourself in St Pauli for this length: it is cheaper than the centre, downhill to the harbour ferries and the Fischmarkt, and the nightlife is on the doorstep rather than a taxi away. Book Miniatur Wunderland and the free Elbphilharmonie plaza slot before you travel, and buy an HVV multi-day ticket, which covers the U-Bahn, the S-Bahn and the harbour ferries alike. Aim to include a Sunday for the Altona Fischmarkt, which opens at 5am in summer, 7am in winter, and shuts at 9.30am. Day one is the warehouse district, day two the centre and the lakes, day three the tunnel, the ferry and Ottensen, day four the museums, Planten un Blomen and a last climb up the Michel.