Altstadt, more precisely Hamburg-Altstadt – as not to be mistaken with Hamburg-Altona-Altstadt – is one of the inner-city districts of the Free and Hanseatic City of Hamburg, Germany.

Altstadt is the German language word for "old town", and generally refers to the historical town or city centre within the old town or city wall, in contrast to younger suburbs outside. Neustadt, the logical opposite of Altstadt, mostly stands for a part of the "Altstadt" in modern sense, sometimes only a few years younger than the oldest part, e. g. a late medieval enlargement.