Hannover is the 13th largest city in Germany according to Wikipedia
Places to visit:
Hannover Christmas Market
There are many things in that you can see in Hannover Christmas Market, including Christmas decorations, traditional items, music performance, some games, and of course delicious dishes.
You can go to Hannover Zoo by tram.
St Clement Basilica
This church has a mass in Spanish as well. My husband and I attended the Christmas Eve mass in Spanish.