Nobody is quite sure who dug them. That's the whole point. On the farm of Ægissíða, right by the town of Hella in South Iceland, a set of man-made caves has been carved into the ground, and people have been arguing about their origins for centuries.

Some believe the caves are older than the Norse settlement of Iceland. Were they made by Celts? Were they a place of worship? The Caves of Hella team lays out the questions and lets you draw your own conclusions, which is more honest than most history tours manage.

What you'll see on the Caves of Hella tour

Five of the caves are open to the public, and this guided tour takes you through them and around their surroundings in about an hour and ten minutes. Inside, look for:

• Ancient crosses cut into the rock
• Wall carvings
• Seats carved directly out of the cave walls

The operator describes the caves as Iceland's oldest archaeological remains still standing. Whatever their true age, standing in a room someone hollowed out by hand, long before anyone thought to write it down, is a very different experience from looking at a waterfall.

Good to know before you go

You'll walk a short distance between the caves, outdoors, so dress for whatever the South Iceland weather is doing that day. Bring a camera. And, in the operator's own gentle words, you might consider leaving the high heels at home.

It's an easy tour and a short one, which makes it a good break on a Ring Road drive or a day exploring the south. Hella sits on Route 1, so it slots in without much of a detour.

Pro tip: wear flat shoes with some grip. The walk is short, but the ground between cave entrances is outdoors and weather has a way of turning grass into mud.