Larissa was the administrative and ecclesiastical center of Thessaly, located on the right bank of the Peneios River, at the junction of major Thessalian routes. The city suffered from an attack by the Ostrogoths at the end of the 5th century but was rebuilt under Justinian I. Constantine VII Porphyrogennetos lists Larissa as one of 17 poleis in the eparchia of Thessaly; in the 8th-9th century it functioned as the metropolis of Hellas. In the 10th century, it fell victim to Bulgarian attacks; in 986 Samuel captured Larissa and carried away the relics of St. Achilleios (allegedly the first bishop of Larissa) to Prespa. Larissa was involved in the rebellion of 1066; in 1082/3 Bohemund besieged Larissa but failed. After 1204 Boniface of Montferrat gave the city to the Lombards; a rebellion there in 1209 was quelled by Emperor Henry of Constantinople. After 1204 Larissa was seat of a Latin archbishop, but by 1222 a Greek, Kalospites by name, was elected Orthodox bishop; Patriarch Manuel I Sarantenos, residing in Nicaea, did not acknowledge the election by the local clergy. In the 13th century Larissa belonged to the despotate of Epiros, but by 1393 it had fallen to the Ottomans. Larissa on the Peneios should be distinguished from Larissa Kremaste in Phthiotis, near the sea, which became an episcopal see named Gardikion. A Byzantine castle has survived on the ancient acropolis; nearby is Frankekklesia, with remains of a Latin church of the 13th century. 

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