This guide explains the oldest working clocks in the world in plain language, with the exact figures and how to work them out yourself.
In England’s Salisbury Cathedral stands a frame of hand-forged iron, built around 1386, that is widely cited as the world’s oldest working clock. It has no face and never did: medieval clocks were bells first — the word “clock” descends from words for bell — and this one’s job was to strike the hours for a town that told time by ear. Restored to running order in the twentieth century, its verge-and-foliot mechanism has accumulated, by the cathedral’s estimate, hundreds of millions of ticks.
Its near-twin at Wells Cathedral, from about 1390, adds theater: an astronomical dial painting the pre-Copernican universe — Earth at center, sun and moon circling — while above it jousting knights charge each other every quarter hour, one unseated for six centuries straight. The original medieval movement, retired in the nineteenth century, still runs in London’s Science Museum, making it a strong rival claimant for “oldest working.”
Prague’s Orloj, mounted on the Old Town Hall in 1410, is the oldest astronomical clock still operating in its original location — a dial tracking sun, moon, and zodiac, joined later by the hourly Walk of the Apostles and a bell-ringing skeleton. Legend claims the city blinded its clockmaker so he could never build another; history, more prosaically, records six centuries of repairs, a near-destruction in 1945, and painstaking restorations since.
The elder statesmen share a maintenance secret: institutions. Cathedrals and city halls kept clockkeepers on the payroll across dynasties, plagues, and wars — continuity no private machine enjoyed. Their accuracy was humble (medieval mechanisms drifted many minutes a day, corrected by sundial), but their persistence is the achievement: iron gears still doing their fourteenth-century job.
Honorable mentions crowd the list — Rouen’s Gros Horloge with movement roots in 1389, Ottery St Mary and Exeter’s astronomical dials, and the Zytglogge in Bern whose performance later helped a young patent clerk named Einstein think about time itself.
Set beside them, the atomic-driven display at itsdately.com is a newborn — but it answers the same civic question those bells did: one town, one time, for everyone in earshot.
Their pre-pendulum hearts deserve the fame: the verge-and-foliot escapement — a swinging bar checked and released by a toothed crown wheel — was medieval Europe’s great contribution to machines, arguably the first mechanism designed to do nothing but divide time evenly. It kept its post for three centuries until Huygens’s pendulum of 1656 improved accuracy a hundredfold overnight, whereupon nearly every old clock was refitted; Salisbury’s fame rests partly on restorers returning it to its original, gloriously inaccurate configuration.
England adds a domestic-scale marvel: clockmakers’ guild records and cathedral accounts show salaried keepers winding these machines through the Reformation, civil war, and blitz — an unbroken maintenance chain longer than most nations’ constitutions, and the real machinery of their survival.
Their endurance reframes what a clock is: not a gadget but an institution’s heartbeat, maintained because a community decided the hour was worth keeping. Six centuries on, that decision still ticks.
Anyone can pay respects: Salisbury and Wells welcome visitors daily, and Prague’s crowds still gather on the hour — six hundred years of audiences for the same mechanical performance.
Frequently asked questions
Related on itsdately: The Speaking Clock: When People Telephoned to Ask the Time · Why Do Clocks Run Clockwise? · Time Capsules: Messages Scheduled Centuries Ahead
Further reading: Salisbury Cathedral