This is what's left of what was THE church in the Middle Ages. It wasn't the cathedral, but they called it that from time to time. It's actually a collegiate church, and was built by Emperor Henry III, whose favorite palace was the one just up the little hill, and consecrated in 1051. It was named after Saints Simon and Jude, whose feast days were on Henry's birthday. In 1056, he entertained Pope Victor there. When Henry died that same year, he had his heart entombed in the church.
It survived war, Reformation, more war, but lost its importance and more important, financial support. After the mediatisation and secularization of the late 1810s, the church fell into disrepair and was sold off to a builder in 1822, who used it for building materials. Only the front "porch" and a few pieces remain, hence the name--more or less the forward/front hall of the cathedral.
旅行者
Looks like a sea creature of a sort
旅行者I thought a head
旅行者A sea head...😊