At the place where the Kamenický stream meets the Sázava river, you can visit the mysterious ruins of the royal castle demolished Kostelec. The ruins are part of a nature reserve and are freely accessible.
The castle was probably founded in the last third of the 13th century by King Wenceslas II, but the first written mention dates back to 1342, when it was held in pawn by Oldřich Medek of Valdek. Although Charles IV bought back the castle in 1356, he soon pawned it again and it had several owners over time. The last of them was Kuneš Rozkoš of Dubá from 1443, who looted in the surrounding area, and therefore the castle was besieged in 1449. It withstood this siege, but a year later, on May 18, 1450, it was besieged again and five days later it was conquered by the army under the command of Zdeněk Konopišťský of Šternberk, who became its new owner. In 1456, serfdom was abolished and he fortified it as one of his military strongholds. Later, he became a leading figure of the anti-Poděbrady opposition, and therefore the royal army captured and destroyed the castle in 1467.
The Walls of Constantinople are a series of defensive stone walls that have surrounded and protected the city of Constantinople (today Istanbul) since its founding as the new capital of the Roman Empire by Constantine the Great. With numerous additions and modifications during their history, they were the last great fortification system of antiquity, and one of the most complex and elaborate systems ever built. They were also the largest and strongest fortification in both the ancient and medieval world.
Initially built by Constantine the Great, the walls surrounded the new city on all sides, protecting it against attack from both sea and land. As the city grew, the famous double line of the Theodosian Walls was built in the 5th century. Although the other sections of the walls were less elaborate, they were, when well-manned, almost impregnable for any medieval besieger.