Considering the Hotel Ockenheim in Mainz?
A VT member wrote the following comment about visiting Mainz:
This is the Burg Staleck... by Venturingnow
This is the Burg Staleck which houses the youth hostel. It's a really lovely place with such a great view! Even if you're not staying at the youth hostel you've got to walk up the pathway and take in the courtyard views of the river from high up on the hill.