Y-ágú-barlang is a striking artificial cave hidden in the Holdvilág-árok valley in the Visegrád Hills of Hungary. Its name literally means 'Y-branched cave,' referring to its distinctive forked corridor carved into greyish-white amphibole-andesite tuff.

The entrance, 215 cm high and 175 cm wide, opens at the foot of the eastern rock wall of the valley, about 30 meters south of a seasonal waterfall. After 6.5 meters the passage splits into two branches - a longer main one running 22.1 m and a shorter side branch of 10 m, giving a total length of 32.1 m. In two spots the ceiling has carved semicircular surfaces that once bore inscriptions, including a Greek Christ monogram, now barely visible beneath more recent graffiti. The atmosphere is quiet and slightly eerie, especially when the nearby waterfall comes alive after rain.

How to get there

• From Pomáz, following a well-used hiking trail through Holdvilág-árok - easy to moderate difficulty, the entrance is easily visible right beside the path

Practical information

• This is not a natural cave but an artificial excavation, possibly linked to early medieval ore mining or ritual use
• Total length: 32.1 m, average passage height around 210 cm
• Two other similar artificial caves lie nearby - Vízesés-alatti-barlang and Weislich-barlang

No one knows for certain who carved this passage or why - theories range from ore or garnet mining to coal prospecting, while researcher István Eszterhás believes it may have served a ritual purpose. Sadly, frequent visitors have left graffiti and paint marks that obscure the ancient carvings.