It is a tall, cylindrical stone ancient structure found mostly in Ireland.
Round towers were built near churches and monasteries between the 900's and 1200's. They were used as belfries for ringing handbells and as places of refuge during raids by Vikings. They vary in height from about 70 to 125 feet (21 to 38 meters) and in diameter from 13 to 18 feet (4 to 5.5 meters). About 70 round towers still stand.
By the 1800's, people had forgotten the purpose of round towers. Some writers suggested that the towers had been built as Phoenician fire-temples, astronomical observatories, or tombs. Other even more outlandish explanations were offered. The true origin of the towers was rediscovered in 1833, when George Petrie, an Irish antiquarian, wrote a comprehensive essay on them.