A small but well-laid-out museum holding finds from across Euboea — Mycenaean pottery from Lefkandi, classical sculpture from Eretria, Roman mosaics, Hellenistic grave reliefs. The standouts are the pieces from the sanctuary at Aulis just south of Chalkis, where in legend Agamemnon sacrificed Iphigenia before the Trojan War.
Not a destination in itself, but a useful hour if you're spending the day in town. Combine with a walk to the seafront for lunch.