Kozlov (castle ruin, Cidlinský hřeben)

Kozlov is a ruined medieval castle perched on a rocky rise of the Cidlinský hřeben ridge, a few kilometers southwest of Lomnice nad Popelkou. Only fragments of walls, ramparts and ditches remain from the original stronghold, yet the site still draws hikers for its dramatic position within the Bohemian Paradise (Český ráj) landscape and for a mysterious rock-cut passage whose original purpose is still debated.

Where exactly is the castle?

The ruins rise above the village of Košov in the Semily district, on the ridge known as Cidlinský hřeben. The easiest way in is on foot, along hiking trails that run through the area near Lomnice nad Popelkou as part of the wider Bohemian Paradise trail network. The castle itself sits on a horseshoe-shaped basalt outcrop, which explains the elongated, irregular layout of the former fortification.

When was Kozlov built?

Archaeologists have dated the castle's origin to the first half of the 14th century, based on pottery fragments found at the site. It served as a noble residence, but its documented history was short-lived. The stronghold was conquered in 1442, and by 1462 records already describe it as abandoned. According to a note by the chronicler Bohuslav Balbín from 1677, a band of raiders occupied the castle after the Hussite wars before being wiped out in 1442 by the regional levy of local nobility.

How was the castle defended?

Kozlov follows a roughly oval ground plan enclosed by a circular curtain wall. A ditch and earthen ramparts protected the site from the north, east and south, while the west side relied on the steep natural slope of the basalt hill, which made additional fortifications there unnecessary. The main entrance was a gate on the southern side. Today only modest remnants of the walls survive, but the line of the ditches and ramparts can still be traced around most of the perimeter.

What is the rock-cut passage about?

The most intriguing feature of the ruins is a narrow corridor carved directly into the rock, which leads into a deep vertical shaft. Its exact function is unclear, though the most likely explanation points to a water source for the castle's garrison. A 2002 survey established that the shaft descends roughly 14 meters. This underground structure, unusual among the ruined strongholds of the region, sets Kozlov apart from other Bohemian Paradise castles and draws particular interest from visitors curious about medieval military engineering.

Is it worth the hike?

Kozlov has been protected as a cultural monument since 1964, a status that reflects its historical value despite its modest remains. The site suits travelers who enjoy combining a short hike with a bit of history — the Cidlinský hřeben ridge offers views over the surrounding hills, and the climb up to the ruins is an easy, pleasant stretch of trail rather than a demanding trek. Bringing a flashlight is a good idea for anyone hoping to look into the rock-cut passage up close.

Frequently asked questions

When was Kozlov Castle built? Pottery finds place the castle's origin in the first half of the 14th century.

Why is the castle in ruins today? It was conquered in 1442 and was already recorded as abandoned by 1462; according to a 1677 note, it had earlier been held by a band of raiders who were eliminated by the local territorial levy.

What is the most notable feature of the site? Beyond the remains of the walls, ditches and ramparts, the highlight is a rock-cut passage leading to a roughly 14-meter-deep shaft of uncertain purpose, most likely linked to a former water supply.

Is the site legally protected? Yes, the ruins of Kozlov have held the status of a protected cultural monument since 1964.

How do you get to the ruins? The castle stands above the village of Košov in the Semily district, near Lomnice nad Popelkou, and is reachable via hiking trails crossing the Cidlinský hřeben as part of the Bohemian Paradise trail network.