The Cryptoporticus of Reims is is a very well preserved third century AD Roman passageway. At the time, Reims was a Gallo-Roman town known as Durocortorum.
Like other structures of this kind, the Cryptoporticus of Reims was a semi-subterranean arched passageway, the roof of which would have been a walkway. It would have been one of three such passageways surrounding the forum of Durocortorum.
The Cryptoporticus of Reims is an excellent example of this type of Roman architecture, particularly as it is so very well preserved.
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.