#OTD in 1410.
The first known mention of the Prague astronomical clock.
The oldest part of the Orloj, the mechanical clock and astronomical dial, dates back to 1410, when it was created by clockmaker Mikuláš of Kadaň and Charles University professor of mathematics and astronomy Jan Šindel. Later, presumably around 1490, the calendar dial was added and the clock facade was decorated with gothic sculptures.
