The Plakánek Valley runs from Kost Castle past Obora pond to the village of Střehom.
This is a romantic, rocky valley amidst mixed forest, named after the Plakánek family, who burned charcoal here for Heřman Černín in the 17th century. A watermill still stands by the village of Střehom, and the Roubenka spring at the bottom end of the valley is featured in the poems of Fráňa Šrámek. At Plakánek there are also several quarries, stone from which was used to build Kost Castle and the church in Sobotka. Malý Plakánek is a rocky gorge that extends off towards the village of Vesec near Sobotka.