Agios Achillios is a small island in Mikri Prespa lake connected to the shore by a 650-metre floating wooden footbridge — one of the more unusual approaches to any historical site in Greece. The island has a permanent community of a few dozen residents, reed-fringed shores, and at its centre the substantial ruins of a 10th-century Byzantine basilica built by Tsar Samuel of Bulgaria to house the relics of Saint Achillios.
The basilica walls still stand to considerable height, and the three apses of the east end are largely intact. Walking the island takes less than an hour — the track circles the whole shore — and the views back across the lake to the mountains of North Macedonia and Albania are among the best in the Prespa basin. The village taverna serves grilled fish from the lake; beans from Prespa (the region's famous specialty) often appear on the menu.