The Palazzo della Ragione is a medieval town hall in Padua. The building, with its great hall on the upper floor, is reputed to have the largest roof unsupported by columns in Europe; the hall is nearly rectangular, its length 81.5m, its breadth 27m, and its height 24 m; the walls are covered with allegorical frescoes; the building stands on arches, and the upper storey is surrounded by an open loggia, not unlike that which surrounds the Basilica Palladiana in Vicenza.
The Palazzo was begun in 1172 and finished in 1219. In 1306, Fra Giovanni, an Augustinian friar, covered the whole with one roof; originally there were three roofs, spanning the three chambers into which the hall was at first divided; the internal partition walls remained till the fire of 1420, when the Venetian architects who undertook the restoration removed them, throwing all three spaces into one and forming the present great hall, the Salone. The new space was refrescoed by Nicolò Miretto and Stefano da Ferrara, working from 1425 to 1440.
A tornado destroyed the roof and damaged the building on 17 August 1756.
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.