Lancaster is a historic city located in the county of Lancashire in northwestern England. The city is situated on the River Lune and is home to Lancaster Castle, which was built in the 11th century and used as a prison until 2011. Lancaster also has a rich maritime history, and the Lancaster Canal runs through the city. The city is home to the University of Lancaster, which is one of the top-ranked universities in the UK. The population of Lancaster is approximately 52,000.