Years ago there was a market on top of Alster when it froze over in the winter, until one year when there was too much weight and not think enough ice. Well the Ice broke and many of the people fell into the icy water and died.
There are increadible shop all around it, and the ice cream is great! If you get too warm in the summer there is a subway station under the Alster that makes you feel like you have AC again!