The public transport system of Hamburg offers a "Hamburg Card", available for one, three or five days, which allows to travel within the city of Hamburg by the urban/suburban railway system or bus.

You can buy a Hamburg CARD from HVV ticket vending machines, at HVV service centres, on board buses and at the Tourist Information Centres (Hauptbahnhof/Central Station, Harbour, Airport).

Prices and further explanations can be found here.