There are 4 "official" detention centres for foreigners in Greece, one on the island of Samos, near the Turkish coast, and two near the land border with Turkey, one in Athens. A fifth, Pagani on the island of Lesbos, was closed following the highlighting of particularly appalling prison conditions.
But there are also many unofficial places of detention or police cells in order to police stations or places open occasionally in warehouses or military installations. All these places, official or unofficial, are characterized by overcrowding (60 prisoners in a cell designed for 20, or 1000 prisoners in a centre designed for 300) and poor living conditions (poor hygiene, inadequate food, no heating) often abuses, and always a lack of legal information.
The European Court of Human Rights condemned Greece in 2009 for his conditions of detention, but the system continues.