Round Towers
a class of tall narrow circular edifices, tapering somewhat from the base upward, and generally with a conical top, from 60 to 130 feet in height, and from 20 to 30 in diameter. With the exception of three in Scotland, they are peculiar to Ireland.
The doors are from 6 to 20 feet from the ground, the windows small. The interior contained no stairs, but the successive stories were reached, like the doors, by means of ladders. Authorities are now pretty well agreed that these towers were the works of a Christianized race erected as places of refuge and as watch towers. They date from the 8th or 9th to the 13th century.