Širvintos City, 5 towns – Bagaslaviškis, Čiobiškis, Gelvonai, Kernavė, Musninkai and 485 villages are in the municipality.

The biggest rivers of the region are Neris, Širvinta and Musė.

There are 28 lakes; the largest of them is Alys, which covers 1.65 km2 (0.64 sq mi), and the deepest is Gelvė, which is 25 m (82 ft) deep.

In the territory of the region are Kernavė’s Historical Reservation, botanical reserves for growing cranberries in Alionys, Bartkuškis (there's an old castle) and Lygaraistis, 6 parks and 2 nature monuments (Staškiūniškiai Larch and the stone with a “devil’s footprint” in Dūdai).

According to the population census of 2001, 20,207 people live in the region: 9,545 men and 10,662 women.