Nasielsk is a small town in Masovian Voivodeship, Poland. It is located approximately north of the Polish capital Warsaw, on the Warsaw-Gdańsk rail line and serves as a railway junction. In 2020, the population of the town was estimated at 7,650 residents. History An early Lechitic (proto-Polish) fortified settlement was built in the 9th century, and the region became part of the emerging Polish state in the 10th century. Nasielsk was first mentioned as Nosidlsk in 1065, in the so-called Mogilno Falsification of King Boleslaus II the Generous for the Benedictine Abbey at Mogilno. As the document states, the gord of Nosidlsk was an important center of defence, trade and administration. In the past, the name of the town was spelled in different forms: Nasilzco, Nosidlsk, Nosylsk, Nosydlsk, Nosielsk, Nosselia, Nosidlsko, Nasidlsko, Nosilsko, Nasilsko, Nasylsco. In 1155, a document issued for Duke Boleslaus IV the Curly confirmed the existence of the gord at Nasielsk, stating that Nowa Wies near Nasielsk was granted to the abbey of Czerwińsk nad Wisłą. In 1257, Duke of Siemowit I of Masovia granted one-third of Nasielsk to the Czerwinsk Abbey. By the late 13th century, Nasielsk emerged as the seat of a castellany. The first document that confirms this fact was issued in 1297, with the notice of "comes Thomas castellanus de Nosylk”. On November 11, 1386, Janusz I of Warsaw granted the remaining part of the town of Nasielsk (civitas Nostra Nosielsko) to the knight Jakusz of Radzanow (Prawdzic coat of arms). Jakusz, who came to be known as Jakusz Bialy of Nasielsk, became the castellan of Nasielsk, and the town remained the property of his family until 1647. The coat of arms of Nasielsk is based on the Prawdzic symbol. The town with its wooden church of Saint Adalbert of Prague burned down in 1440, and five years later a new brick church was erected. Nasielsk for centuries remained in the private hands of the Nosielski and Wessel families. In the mid-18th century, the first synagogue was built, and in 1795, following the Third Partition of Poland, Nasielsk was incorporated into the Kingdom of Prussia, where it remained until 1807, when it became part of Napoleon's short-lived Duchy of Warsaw, and afterwards it was incorporated into Russian-controlled Congress Poland in 1815. Until 1866, Nasielsk was a private town. In 1877, a rail line from Warsaw to Gdańsk via Nasielsk was completed. In 1918,