Heraklion 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.