The not very distintive ruin of the Gothic tower named Košťál (14th century) is situated on the hill to the southwest from the village of Košťálov. It was founded by the Valdštejn family around 1361 and it was protected from the south and north with a system of moats and walls. As for these structures, there are not many remnants: parts of base walls that are hidden in grown bushes and trees, shallow holes left after cellars and a deeper hole - the former well. There used to be a tower, located on the elevated southern part. At the end of the 15th century the property was connected to Semily. In 1514 the castle is mentioned as a deserted castle.

Locality: 5 km to the southeast from Semily, near Košťálov.

Legend about confusing horseshoes:
A long time ago, there was an enemy who was trying to conquer Košťál Castle for such a long time that the owner really did not know what to do. He was thinking day and night how to save the castle against the persistent enemy. Then a storm was approaching one evening and the master got a good idea: he knew that the enemy would try to hide in tents. Hence, he ordered his people to fit the horses with their shoes the wrong way round and he went round the castle several times. On the following day, the enemy army was away. When they heard the beating of hoofs and spotted the shoe prints, they thought that abundant reinforcements arrived and decided to give up the siege.