Heraklion (Greek: Περιφερειακή ενότητα Ηρακλείου) is one of the four regional units of Crete. The capital is the city of Heraklion.
The regional unit of Heraklion borders on the regional units of Rethymno to the west and Lasithi to the east. Farmlands are situated in the central and the northern parts, at the coast and in valleys. The mountains dominate the rest of the regional unit, notably the south. The main mountains are parts of Ida or Idi Mountains to the west and Asterousia in the south. The regional unit includes the island of Dia to the north.
Except for the mountains which receive mild to cool winters unlike northern Greece, the warm to hot Mediterranean climate dominates the regional unit.
Within the Heraklion regional unit's boundaries are a number of significant Neolithic and Minoan settlements, most notably the ancient palace complexes of Knossos and Phaistos. While both archaeological sites evince Neolithic habitation, it is the rich finds of Minoan civilisation, which flourished approximately 2000 to 1600 BC, that command the greatest scholarly attention.