Round Tower, Andernach

The Round Tower (Runder Turm) is a large defensive tower in Andernach, Germany, the town's keep and schauinsland (literally "look into the country"). The castle and the town walls were called that because they provided a far look into the surrounding country to see enemy troops approaching in time. It dates to the 15th century, and was a former watch tower in the town fortifications at the northwest corner of the medieval town wall.

Building data from Wikidata (CC0); heights normalised. Summary from Wikipedia (CC BY-SA).