Mega Spilaio, Greek Orthodox monastery in Kalavryta, Greece

Mega Spilaio is an eight-storey monastery complex set into the mouth of a large natural cave in the 120-metre cliff of Mount Chelmos, above the Vouraikos gorge about 11 km from Kalavryta. Its stepped buildings rise from a long tan wing with arched windows to a cream-yellow block with five storeys of balconies, beside a stone facade with a painted arched entrance and a lower wing with a wooden pergola. The katholikon is cut into the rock.

The monastery was founded in 362 AD and survived multiple destructions over the centuries. In 1943, German forces attacked the site, killed monks, and burned the structure, marking a turning point in its modern history.

The monastery houses a wax and mastic icon of the Virgin Mary, traditionally linked to Saint Luke, which draws pilgrims throughout the year. Visitors can observe this revered religious image within the complex and understand why people continue to gather here for spiritual devotion.

The monastery stands about 10 km northeast of Kalavryta, on the road linking the Patras–Athens highway with the town, above the Vouraikos gorge at roughly 900 m. The eight-storey complex is built into the cave mouth, so expect stairs and stepped terraces between levels. The katholikon is cut into the rock, with 1653 wall paintings in the main church and early 19th-century ones in the narthex.

Pausanias records that the daughters of Proetus took refuge in this cave during their madness, long before Christian hermits occupied it. The spring beside the icon, now a marble hagiasma called "the Spring of the Girl", is linked in tradition to the shepherdess Euphrosyne, honoured as a saint for leading the monks to the icon.