Burg Altena
Burg Altena

Where: Altena, Germany

Start of construction: 12th Century

End of construction: 15th Century

Most important renovation: 20th Century

Accessible: yes, museum

Important fact:

Destroyed in 1455 by fire and partially rebuilt. Current shape came after renovation around 1918. Since then, a youth hostel has been located in the castle; the oldest in Germany.