Mithymna (ˈmiθimna) (Μήθυμνα, also sometimes spelled Methymna) is a town and former municipality on the island of Lesbos, North Aegean, Greece. Since the 2019 local government reform it is part of the municipality of West Lesbos, of which it is a municipal unit. Before 1919, its official name was Μόλυβος - Molyvos; that name dates back to the end of the Byzantine Era, but is still in common use today.
It is located NE of Eressos, N of Plomari and NW of Mytilene.
The town (pop. 1,399 at 2011 census) is on the northern part of the island, just some 6 km north of the popular beach town of Petra. One of the most noticeable features of the town is the old Genoese fortress on the hill in the middle of the town. The town's agora is located on the uphill road to the fortress and is popular among tourists, with many historic shops, cafés and restaurants.
The municipal unit of Míthymna stretches eastward from the town along the northern part of the island; it is the island's smallest municipal unit in land area at 50.166 km2. Its population was 2,255 at the 2011 census. The next largest towns in the municipal unit are Árgennos (pop. 240) and Sykaminéa (207).
Molyvos Beach is one of the Blue Flag beaches in Lesbos. The shoreline is pebbled, but the seabed consists entirely of soft sand and remains shallow for a considerable distance. The agora and fortress are visible from the beach.
As Methymna, the city was once the prosperous second city of Lesbos, with a founding myth that identified an eponymous Methymna (Greek: Μήθυμνα), the daughter of Macar and married to the personification of Lesbos.
Very little is known about Methymna in the Archaic period. The story of Arion and the dolphin, which involves the Corinthian tyrant Periander and is evidently set at the turn of the 7th century BCE, suggests that Methymna was already a prominent city with far-reaching contacts across the Greek world at this period. Herodotus tells us that at some point in the Archaic period, Methymna enslaved the city of Arisba on Lesbos: this will have greatly increased the territory of Methymna, as well as giving it access to the fertile land around the Gulf of Kalloni.