This arch is an entryway into the castle ruins of Rheinfels castle in St. Goar, Germany. This is one of the medieval castles of the Rhine River Valley, and you can go inside and explore the ruins a bit. It is very cool to get an idea of what life was like in these castles, it seems like a hard life of defending your territory, cramped and not-so-sanitary living. Not as romantic as we make it out to be today!
I liked this photo because of the scale. You can see Patrick and Brandon inside the arch, and get an idea of just how big it was. They needed to be able to ride through on horseback with flags, etc. so it had to be tall. One more use of the arch, not as decorative as the Rennaisance arches in the Italian courtyards, but interesting just the same.
You know, there's just not enough riding on horseback with flags in the world any more.