Porte Mars is an ancient Roman triumphal arch in Reims. It dates from the third century AD, and was the widest arch in the Roman world.
The arch stands 32 metres long and 13 metres high. It was named after a nearby temple to Mars. The arch has many highly detailed carvings on its exterior and on the ceilings of its three passageways. Local folklore says that the inhabitants of Rheims built the arch in gratitude when the Romans brought major roads through their city. It served as a part of castle of archeveque and a city gate until 1544 was closed of it. In 1817, the buildings around it were removed, bringing the arch into full view.
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.