The Koppelpoort is a medieval gate built around 1425. It combines land- and water-gates, and is part of the second city wall constructed between 1380 and 1450. The gate was opened every morning and closed every night by the appointed raddraaiers, “wheel-turners”. A minimum of twelve wheel-turners were press-ganged to operate giant hamster-wheels. It was a dangerous task; if they did not begin walking simultaneously, one could fall, dragging the rest along with potentially fatal results.
The koppelpoort was never breached. It was given its current appearance during the restoration by Pierre Cuypers in 1885 and 1886. The latest restoration was completed in 1996.