Up on a cliff in Ardre parish is Kaupung's castle. Yes, castles are what former fortifications are called here on Gotland. A forest path leads you around the ancient castle.
On Gotland there are about 100 ancient castles, of which about 30 are cliff castles like Kaupung's castle. Ancient castles have often had different functions during different times. They may have been checkpoints, strongholds or fortified farms during turbulent times and trading posts, customs stations, courthouses, places of worship or perhaps animal sanctuaries during quieter periods. Not all castles have worked at the same time or for the same length of time. Surveys show that most were built and used mainly during the Iron Age.
source Länsstryrelsen