Ashby-de-la-Zouch (/ˌæʃbɪ dələ ˈzuːʃ/), often shortened to Ashby, is a small market town and civil parish in North West Leicestershire, England, within the National Forest. It is a sister city with Pithiviers in north-central France and lies close to the Derbyshire border. The population of the town according to the 2001 census was 12,758, which increased to 13,759 in the 2011 census. Ashby-de-la-Zouch Castle was of importance from the 15th to the 17th centuries. In the 19th century the town became a spa town and before the growth of Coalville it was the chief town in northwest Leicestershire.