Its administrative seat and largest town is Legionowo, which lies 22 kilometres (14 mi) north of Warsaw.

The only other town in the county is Serock, lying 17 km (11 mi) north-east of Legionowo.

Both the road and the train connection pass through the national reserve forest which separates Legionowo from Warsaw and is a favorite weekend walk and biking destination.

On the opposite side of Legionowo is the Zegrze Reservoir, created in 1970 with the building of a river dam, now a popular leisure destination.

The village of Jabłonna, between Legionowo and Warsaw, housed the largest population of private production and greenhouse businesses in communist times, making the village the richest in Poland at that time and continuing to this day in the form of a thriving business community.