Castle
Depending on the exact definition, the number of castles varies and more castles are still being discovered. The numbers below are rough, and it is difficult to find estimates for some countries like Italy and Spain though they have many castles. Imitation castles have been built in the 19th and 20th century, like Neuschwanstein or some places in the United States but these are not considered genuine castles as they were not meant to be defensive.