The area was the site of several battles during "The Deluge", the 17th century war between the Polish–Lithuanian Commonwealth and Sweden. In 1655 a short-lived treaty with Sweden, the Union of Kėdainiai, was signed by two members of Radziwiłł family in their Kėdainiai castle. While little remains of the Radziwiłł castle, the crypt of the Calvinist church (1631) houses the family mausoleum, including the tombs of Krzysztof Radziwiłł and his son Janusz.