Łydynia is a river of north-eastern central Poland, a left tributary of the Wkra at the town of Sochocin, with an overall length of 72 kilometers.http://portalwiedzy.onet.pl/54590,,,,lydynia,haslo.html (Polish language)
The river flows past Ciechanów and its ancient Mazovian ducal castle. Its own tributaries include the Giedniówka, the Dunajczyk, the Stawnica, and the Pławnica.
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