Change DB:The name of the venue in Frankfurt where Led Zeppelin had to cancel their concert for 3/10/70 was "Jarhunderthalle." The concert was cancelled due to riots that occured at the Jethro Tull show on 2/21/70.
Here's a reference to the cancelled show in a June 1970 Stars and Stripes report:
Here are a few photos of the Jahrhunderthalle: