The ruins of Lichnice Castle are on the edge of the Iron Mountains in the municipality of Třemošnice. The castle was probably constructed as a royal base in the first half of the 13th century. It was first mentioned in 1261, when it was in possession of Smil of Ronow, who called himself 'Smil of Lichtenburg' and thereby created the 'von Lichtenburg' family.
The castle had a triangular floor plan with two residential towers. In the 14th century, alterations were made, and it was reacquired by the Bohemian Crown in 1410. It was conquered in 1421, during the Hussite Wars, and besieged unsuccessfully in 1428.
In 1490, the castle and estate of Lichtenburg were acquired by the Trčka of Lípa family, who rebuilt the castle in a late Gothic style.
The edifice lost its importance at the end of the 16th century, and the fortifications were dismantled. By 1700, it was already described as a ruin.
References:The Clementinum is a historic complex of buildings in Prague. Until recently the complex hosted the National, University and Technical libraries, the City Library also being located nearby on Mariánské Náměstí. The Technical library and the Municipal library have moved to the Prague National Technical Library at Technická 6 since 2009. It is currently in use as the National Library of the Czech Republic.
Its history dates from the existence of a chapel dedicated to Saint Clement in the 11th century. A Dominican monastery was founded in the medieval period, which was transformed in 1556 to a Jesuit college. In 1622 the Jesuits transferred the library of Charles University to the Klementinum, and the college was merged with the University in 1654. The Jesuits remained until 1773, when the Klementinum was established as an observatory, library, and university by the Empress Maria Theresa of Austria.