Round Towers
Round towers are a common architectural style in Ireland (we saw quite a few of them), but very rare outside the island. Only two exist in Scotland -- Brechin and Abernethy towers. These narrow round towers -- the purpose of which is still argued -- are usually atteched to churches or cathedrals.
Storehouse? Lookout tower? Belltower? Refuge? It's not clear. The idea that anyone would take refuge in a chimney with wooden floors when attacked seems ridiculous --anyone wanting to get rid of the monks would simply light the thing on fire and it would act like a furnace. Not a good plan, obviously. Storehouse? Well, the doors are usually 5' or more above ground level, and the internal floors are reached by ladders which can be removed or pulled up, so they would be reasonably secure. Watchtowers? They do ten to stand 100+ feet tall, and would provide excellent visibility to the surrounding countryside. Perhaps signal towers? Or prisons? Who knows. It is likely they played some role in early christianity, but no one is really sure..
Towers in Scotland
Only four examples of round towers exist outside of Ireland. In Scotland, they appear to have the same peculiar architecture as the Irish towers--originally with capped roofs, windows facing the cardinal directions, door facing west, wooden floors reached by ladders, doorways high off the ground.