Originally known as St Patrick's Well Lane after a 12th century well, it was renamed in the 1700s after the Royal House of Nassau. The well was connected by legend to St Patrick who struck the ground with a staff to bring water bubbling to the surface. It dried up in 1729. After the demolition of the Thing Mote in 1685, the earth was used to build up the level of Nassau Street by eight feet to prevent it from flooding. In 1842, the tall wall of Trinity College was lowered and surmounted by the railings visible today.