Mechanical clocks first appeared in medieval Europe, often mounted in towers for public use.

The longer version

Weight-driven mechanisms with an escapement appeared in European monasteries and towns around the thirteenth century, probably developed to ring bells at fixed hours for prayer. They needed no water or sunlight, which made them usable through winter and at night. The verge escapement regulated a falling weight's release.

Installing them in towers turned time into public property: a bell could call workers, open markets and close gates. Early examples lacked minute hands because nobody needed that precision, and errors of a quarter hour daily were tolerated. Possession of a public timekeeper became a mark of civic pride, and towns competed to build grander dials.

Where this entry sits

These facts wander through clocks, calendars, time zones, and the long human effort to measure passing hours. You will find leap years, odd month lengths, ancient sundials, and the reasons modern timekeeping works the way it does. The full list sits on the Time and Calendars page, where every entry is listed in order.