landscape hemmed in by mountains, broad tracts of forest, and important water resources: these are the main natural features of Kastoria and its region.

The city lies virtually at the centre of a plateau bounded by Mts Vermion, Askion and Grammos. The Aliakmon - the longest river in Greece - and its tributaries have created a large number of fertile, cultivable plains in the areas. The climate is a 'continental' one: Kastoria typically has rainfall in the autumn and spring, and heavy snowfall in a fairly cold winter.

Many aspects of the city's character are due to the lake. From the first it provided the region with natural defences, and this meant that settlers chose this particular site even in prehistoric times. It was also an important natural larder: there are references to the fisheries on the lake from as early as the 12th century A.D. Last, but not least, it was a habitat of beavers: this, allied to the mountain environment and continental climate, favoured the growth of a fur trade - a vital branch of the city's commercial activity even today.

One further factor other than the lake that contributed to Kastoria's natural defences was the lie of the land. The surrounding hills form a naturally sheltered environment, access to which is fairly difficult. This 'natural fortress' was later strengthened by building almost impregnable walls, which accounts for the fact that Kastoria was from of old a key point in the region.

However, the city's geographical position also allowed it to keep in touch with the region's other main centres and the Byzantine Empire as a whole.