I picked up these two stereographic cards last year at the same antiques store where I purchased the old copy of The Herbalist Almanac. They weren't in splendid condition, but I couldn't resist because (1) they were inexpensive and (2) I am fascinated by the history of buildings and cities along the Rhine.1
The caption on the top card states: "Bingen and the Vineyards along the Rhine, Germany."
The caption on the bottom card states: "The Mouse Tower and the Ruin Ehrenfels, Along the Rhine, Germany."
How that building came to be known as the Mouse Tower is a bit of a folk legend. In a nutshell: Hatto II, the archbishop of Mainz in the late 10th century, was a cruel and murderous man who stockpiled grain and would not feed his people when a famine struck. On the pretense of finally giving them something to eat, he tricked all of the peasants into entering a barn and then locked them inside and burned them to death, cackling "Hear the mice squeak!" as they died.2 Soon afterward, Hatto II was attacked by an army of mice. He took his boat across the river to his tower, hoping the mice would not follow him across the Rhine. But they did. The mice stormed his tower and ate him alive. Thus was born the Mouse Tower.
For more-detailed examination of the Mouse Tower folk tale, including a long poem version of the story, see Curious Myths of the Middle Ages/Bishop Hatto on Wikisource.3 The below illustration is from that web page:
1. One of my favorite antique books, purchased years ago at The York Emporium on one of my very first trips there, is the 1882 volume "The Heart of Europe: From the Rhine to the Danube". It's filled with detailed illustrations of sites that simply no longer exist as they were 125+ years ago.
2. As you might have guessed, this is not exactly a folk tale for children.
3. Wikisource is an online library of free content publications. As of June 1, 2011, it had more than 200,000 English-language texts in its library.