Osiek, Gmina Joniec
Osiek  is a village in the administrative district of Gmina Joniec, within Płońsk County, Masovian Voivodeship, in east-central Poland. It lies approximately  west of Joniec,  east of Płońsk, and  north-west of Warsaw. This gentry village ("wieś szlachecka", i.e., owned by a noble) became part of the  in the second half of the XVI. Between 1975 and 1998, this place belonged to the Ciechanów Voivodeship. References

Osiek