Almost toppled off the trusty velocipede when I first clapped eyes on this place last year.
This is the Don Bosco Catholic Youth Centre, an organisation supported by Diocese of Mainz and providing conference facilities and accommodation for groups of up to 60.
Numerical, not chronological.
My first instincts were confirmed when it won first prize in the 2011 Rhineland-Palatinate architectural competition.
Architect is Angela Fritsch from Darmstadt – check out her gallery. Good stuff.
Mainz Daily Photo 
Here I am again! The blog and posting is working again on my iMac. Lovely clean lines on the building. I, however, like the grandiose architecture of Gehry.
I got here the roundabout way again from a link on your Wheels photo. Guess the mystery will remain unsolved. I think I prefer the grandiose architecture of Gehry, tho.