Furlong

The furlong is a unit of distance measuring that have had various definitions over time. Vysogota of Corvo said to Ciri that, during the events of the Witcher saga, the generally agreed upon reckoning is that 420 furlongs are the equivalent of about 50 miles.

Trivia

 * Assengard in Nazair is four hundred furlongs north to Mil Tracta.