The burghers of the Old Town bought a corner house on the market square in 1338 and turned it into a town hall; they added the tower, the oriel chapel of the Virgin Mary (consecrated 1381), and over the following centuries swallowed four more houses along the north side. The neo-Gothic east wing was shelled and burnt out in the last days of the German occupation in May 1945 and never rebuilt — the gap on the square is a war ruin, not a design.
The astronomical clock was installed in 1410, made by the clockmaker Mikuláš of Kadaň to a design by Jan Šindel, master of astronomy at Charles University; the calendar dial below is a 19th-century replacement by Josef Mánes (the one in place is a copy) and the Apostles above date from later rebuilds. The astrolabe dial is the part worth standing under: it shows the sun and moon against the zodiac, Old Bohemian time on the outer ring of Gothic numerals, and Babylonian unequal hours. The Apostles process on the hour, 09:00 to 23:00. The show itself lasts under a minute and is the least interesting thing about the clock.
The paid visitor route goes up the tower — there is a lift as an extra — to a gallery 42 m up looking straight down on the square’s plan, and takes in the chapel with its view of the clock’s mechanism, the council chamber and the Romanesque and Gothic cellars, which are the ground floors of 12th- and 13th-century houses buried when the Old Town was raised several metres to defend against Vltava floods. That is the single best thing here for anyone interested in what medieval Prague physically was: you walk into a street level that was abandoned around 1300.
Book or arrive at opening: the first hour after opening is half price.
