On the acropolis of ancient Eressos overlooking the coastal area and beach are remains of pre-Hellenistic walls, castle ruins, and the AD 5th-century church, Ayios Andreas. The church has a mosaic floor and a tiny adjacent museum housing local finds from tombs in the ancient cemetery.
- Address: 1 km (½ mi) north of Skala Eressou, Skala Eressou, Lesbos, 81105
- Phone: 22530/53332
- Cost: Free
- Hours: Tues.–Sun. 7:30–3:30
- Location: Skala Eressou