It is located 7 kilometers northwest of Trikala in the Thessalian Plain and close to the river Pineios.

The first official reference to Mertzi is in an 1163 document of the Holy Bishopric of Stagai, and it is again found in several 14th-century monastic property deeds.

In 1204, after the Fourth Crusade, Thessaly was assigned to Boniface of Montferrat and in 1225 was conquered by Theodore Komnenos Doukas, ruler of Epirus.

From 1271 to 1318 it was an independent despotate that extended to Acarnania and Aetolia, run by a branch of the Epirote Komnenos Doukas dynasty.

He used to throw his loot into a stream that led from Metsovo, and let the current carry them to the lake near Mertsi, where his aide gathered them, thus avoiding any checks by the Gendarmerie.

The Kefalovryso residents are mainly occupied in the field of agriculture, particularly in the production of corn, wheat and cotton.

Many of them are also working in the nearby city of Trikala in a variety of private enterprises or as civil servants.