Home Page



Some Irish history

Why is the Kilkenny round-tower stable?

It is remarkable that the great ancient round tower in Kilkenny is still standing — as is true of other impressive specimens throughout the land — and remarkable that it remains in such immaculate condition.

The conical roof and inner spiral staircase are missing from the Kilkenny tower — but they were both removed in later remodeling operations.

The tower is 100 feet (30 meters) tall, just less than 15 feet (4.5 meters) in diameter, and is set into graveyard clay. Excavations in the 1800's revealed its foundation to be only two feet deep. The tower is about a thousand years old. Its walls, of limestone, are about a meter thick at the base, thinning a bit upward. The structure is heavy, tall and thin.

In John Bradley's "Discover Kilkenny," he writes: "Theoretically, such a foundation on graveyard clay is inadequate, but the building has stood the test of time, probably because it is essentially a cylinder — and cylinders tend to be very stable because all the stress is conveyed directly to the ground."

But any structure that stands upright conveys all stress directly to the ground — it's not a feature peculiar to cylinders.

There doesn't seem to be a proper explanation for the fact that the Kilkenny round tower stands. Yes, it tilts a little bit, but not much — not as much as some of the gravestones in the churchyard around it.