Konstancin-Jeziorna [kɔnˈstaɲt͡ɕin jɛˈʑɔrna] is a spa town in Piaseczno County, Masovian Voivodeship, Poland, with 17,566 inhabitants (as of March 2011, according to GUS).

The town is known for its historic villas as well as newly built mansions, a shopping center in a restored 19th-century mill and is the home of the American School of Warsaw.

[1] During World War II, it was occupied by Germany, administratively part of the General Government, in the Warsaw District.

The Wilanów railway station from the second half of the 19th century, located at 64 Warszawska Street, has been preserved in the district (since 2010, there is a branch of the post office No.

Klarysew [pl] was popular among the political elite of the Polish People's Republic and some leading officials such as Eduard Gierek had their houses there.