Hartenštejn (German: Hartenstein) is one of the forgotten castles of the Karlovy Vary Region. It was allegedly founded in the second half of the 15th century by Jindřich of Plavno. It was a castle of the nobility, as well as military strongpoint due to its thorough artillery defence. According to records, the castle was abandoned from 1609 on; nonetheless, remains of the castle towers, the castle moat with a dike, cellars, as well as ruins of other buildings have been preserved to our time.
The first mention of the Late Gothic castle dates back to 1473. It was built by Jindřich of Plavno. Its main purpose was not to serve as a residence of the nobility but as a military strongpoint and its appearance corresponds to this purpose. The Lords of Plavno often pledged the castle and in 1521, the castle was acquired by Jindřich Mašťovský of Kolovraty. Thenceforth, the castle changed its owners quite frequently and its significance was declining. It was abandoned in 1554 and 19 years later, it was denoted as deserted. Shortly after, however, it was temporarily occupied by Adam Štensdorf of Štensdorf senior.
The castle became a part of the nearby Andělská Hora (Angel Mountain) in 1609 and its ultimate dilapidation soon followed. The castle ruins were partially uncovered and one of its towers was somewhat untowardly reconstructed and roofed in the first half of the 20th century. The rather small square-shaped castle was built on the top of a hill; its northern, southern, and eastern side were guarded by semi-circular battery towers erected in the middle of the castle walls. The towers were equipped with key loopholes and an arched basement. The western side was dominated by an extensive multi-angular structure near the castle gate guarded by a small semi-circular bastion. A small-size basement house stood at the corner next to the south battery tower. Water supplies were secured by means of a well, which has been preserved to our time and it may be found at the entry to the east tower.
Excavations conducted in the 20th century uncovered a free-standing structure in the courtyard. The access road wound in a parallel around the hilltop, its final part led across the castle mound in front of the moat and along all three battery towers. Hartenštejn Castle represents a quite sophisticated artillery defence system deploying battery towers and as such, it shifts the beginning of high-quality Late-Gothic defences back to the 1460’s and 1470’s.