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The water drainage system (qanat) of Hortiatis

The Qanat is situated in Agia Paraskevi region, at an altitude of 575 - 565 m, at the bottom of a dry valley in today’s Hortiatis village on the homonymous mount. Mount Hortiatis rises southeast of the city of Thessaloniki in Central Macedonia in Greece, peaking at 1,201 metres. The mountain's landscape is forested, with part of these woodlands characterized as National Park and Wildlife Refuge and also Natura 2000 site.   

The wider region geologically is part of Perirodopiki zone and particularly of the unity Aspri Vrisi – Hortiatis. In the lower part of the unity Permo-Triadic metaklastic and carbonate sediments exist. In the upper part of the unity deep sea sediments are present, like black cherts, red argilic shales, black graphitic phyllites and quartz shales. Additionally, metamorphic rocks of acidic magmatic origin exist.

In the hydrographical network of the wider area there are no rivers present with a year-long permanent flow, which must be attributed to the lack of surface, natural water sources of adequate supply. This fact, in combination with the climatic conditions in the greater area of Thessaloniki, that are characterised by dry-warm and humid-cold seasons, forced city administrators of the Roman period in the beginning of 4th century AD to build water-collective systems, qanat, in order to meet the growing needs for water supply of Thessaloniki.

Indeed, this is the largest known qanat in Greece with a total length of construction (including the tunnels and the pipes) extending to ~ 20 km down to the Thessaloniki city.