Phthiotis is one of the regional units of Greece. It is part of the administrative region of Central Greece. The capital is the city of Lamia. It is bordered by the Malian Gulf to the east, Boeotia in the south, Phocis in the south, Aetolia-Acarnania in the southwest, Evrytania in the west, Karditsa regional unit in the north, Larissa regional unit in the north, and Magnesia in the northeast. The name dates back to ancient times. It is best known as the home of Achilles.

Lamia is a city in central Greece. The city dates back to antiquity, and is today the capital of the regional unit of Phthiotis and of the Central Greece region. According to the 2021 census, the Municipality of Lamia has a population of 66,657 while Lamia itself has 47,529 inhabitants. The city is located on the slopes of Mount Othrys, near the river Spercheios. It serves as the agricultural center of a fertile rural and livestock area.