Gniazdowo is a village in the administrative district of Gmina Stary Lubotyà Â, within Ostrów County, Masovian Voivodeship, in east-central Poland.
In 1827, Gniazdowo had a population of 222.
During the German invasion of Poland which started World War II, on September 10, 1939, German troops carried out a massacre of some 20 Poles (see Nazi crimes against the Polish nation).