According to conventional wisdom the great Round Tower at Glendalough was built to protect the religious relics, books and chalices used around the monastery from Viking raiders.
I can't help feeling I would have chosen somewhere rather less conspicuous to store my valuables.
Still I'm sure it was useful as a look-out, and for that traditional use of church towers and minarets, calling the faithful to prayer.
The site was begun in the sixth century by St Kevin, a hermit priest, who moved to the area for its remoteness and serenity. However it was not to be, as his followers soon built a collection of churches, chapels and living quarters in the valley below the site of his hovel. This soon grew and eventually, at the height of its popularity, was one of the main religious sites in Ireland, known to some as the Monastic City.
Poor old St Kevin was eventually reduced to hiding in an almost inaccessible cave, St Kevin's Bed, above the lake. It reminds me of the fate of St Cuthbert of Lindisfarne. Perhaps the cult of celebrity is not such a new thing after all.