The Hohllay, a two-thousand-year-old quarry turned cave

Most of the Mullerthal’s rocks are geology’s work. The Hohllay is largely people’s. It’s a huge cavern in Berdorf’s sandstone, with a rippling roof and openings that let in green light from the woods, and what makes it special isn’t its size but the round marks on the walls. They’re the hollows left behind as millstones were cut out of the rock.

A quarry two thousand years old

visitluxembourg sums it up in one line, calling the imposing cavern a quarry two millennia old. The Romans took building stone from here. In the Middle Ages, like the amphitheatre nearby, it was worked for millstones, and the official listing adds a detail I love. Every mill in the lordship of the convent of Oeren, near Trier, was fitted with millstones from this very spot.

Oeren is the same name borne by Irmina of Oeren, the woman from Trier who in 698 gave Willibrord the estate at Echternach where the abbey grew. The region is called Mëllerdall, the valley of the millers, after the many mills on its streams, and the Hohllay was one of the workshops that kept them turning. Seen that way, it’s a slice of the area’s economic history tucked inside a cave.

What you’ll see inside

A wide space, cut into the Luxembourg sandstone that shapes all of Berdorf’s landscape. On the walls, the circular millstone scars are easy to spot, as the Mullerthal Trail website points out. The official listing gives no measurements or opening times, because it’s an open hollow in the woods rather than a deep cave with guided visits.

Facing it, some 50 m away, is the Breechkaul amphitheatre, likewise a hollow left by medieval millstone quarrying, which became an open-air theatre in 1979 and stages concerts in summer. Every year, on the first Sunday after 2 November at 10:45, a St Hubert mass is said there to the sound of hunting horns, famous across the region and over the border, according to visitluxembourg.

If you are staying the night, see the best hotel deals in Berdorf for your dates: the well-placed rooms go fast.

The stone that made the millstones

The Luxembourg sandstone you see in the Hohllay is the same rock as the rest of the Mullerthal. The government portal explains that it formed on the floor of a sea more than 200 million years ago and plays a key role in the region’s drinking water today. If that side interests you, Berdorf’s Aquatower, a 55 m water tower, has an interactive exhibition on water and geology and a viewing platform at 50 m, free with the LuxembourgPass. The Mëllerdall geopark, which Berdorf belongs to, joined UNESCO’s global network in 2022, and the Hohllay is a good way to see how that geology turned into a trade.

Think of it as a quarry that became a landmark rather than a cave you explore. It suits a half-hour stop on a longer walk, not a destination in itself, and it’s at its best when you arrive on foot from the gorge side.

How do you get there?

The Hohllay sits on Route 2 of the Mullerthal Trail, on the 6.8 km stretch from Echternach to Berdorf. Coming from town, you first pass the Wolfsschlucht, then follow the Aesbach stream, go by the Perekop rock, cross the Chipkapass on a footbridge and reach the cave. The amphitheatre and the village follow straight after.

By car, the official listing gives the Huel Lee/Amphitheater car park about 200 m away. If you’d rather take the bus, which costs nothing in Luxembourg, get off at Berdorf, Hôtel Pérékop, about 500 m off. Local route E1, 13.5 km, and Berdorf’s 6.6 km Auto-Pédestre circuit also pass it, two good options for a shorter loop without the full Trail.

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How I’d do it

I’d see it as part of the walk from Echternach to Berdorf rather than as a quick stop by car. Arriving on foot, after the gorge and the Perekop, gives it context. And I’d spend a few minutes hunting for the millstone marks, because it’s easy to walk in, photograph the ceiling and leave without spotting them.

There are no opening hours or tickets. The sandstone can be damp and the floor is uneven, so wear shoes with good grip. It works very well with children, as it’s big, open and easy to explain.

So you do not lose the morning at the ticket office, browse tickets and tours in Hohllay on GetYourGuide.

If you would rather go at your own pace, see the car hire deals in Luxembourg: the earlier you book, the more cars are left to choose from.

Before you fix your dates, compare tickets to Luxembourg: the same journey can cost very different amounts from one day to the next.