The Old Town Hall has been standing in the very centre of the city as a symbol of its right and autonomy. In addition, on the front it bears a proud slogan Praga caput regni – Prague, head of the kingdom. It was established due to a privilege by Czech King John of Luxembourg, issued for the Old Prague Town in Amiens on 18th September 1338. The ruler thus fulfilled old desire of burghers and permitted a higher degree of self-government for them. The Town Hall, as we have known it nowadays, rose by joining successively purchased burgher houses or those, which were given as donations and which were modified several times in the course of the centuries. Thus the complex of the town hall buildings has become a mixture of various styles, from the Romanesque style to this age. Despite it has formed a wonderful architectonic unit. Build-up of the tower started at the beginning of half of the 14th century and it was completed in 1364. A town-hall bay chapel was established on the eastern side of the tower. The mighty prismatic tower, 70 m high, four-storied, with an observation gallery and corner spires, has been one of the city symbols till nowadays. Inside the tower, there has been installed a unique piece of medieval technology, the Old-Town astronomical clock. It is located in an outbuilding between two columns in front of the tower’s southern side. It was made by royal clock-master Mikuláš of Kadaň and astronomer Jan Šindel, the Prague University Master, in 1410. We may add clock-master and lock-maker Hanuš, called Růže, as a co-author, who supplemented various other parts in the older primitive astronomical clock, which had only contained a striking machine, a minute machine and a sphere, in 1490 and thus he created the basis of the present sophisticated mechanism. The astronomical clock consists of three, over-installed, parts, apostles’ march, astronomical face, which is heart of the astronomical clock and its highest value and in the lowest part there is a calendar. In May 1945, during Prague rebellion against the Nazi occupants, two wings of the town hall were destroyed and the tower and the astronomical clock were badly damaged. While the ruins of the town-hall wings were removed, the tower and the astronomical clock were repaired.