town, Aylesbury Vale district, administrative and historic county of Buckinghamshire, England. The town lies at the centre of a rich clay vale. It was once an important market town for ducks and dairy produce but is now an expanding centre of industry, which includes food processing, light engineering, and especially printing. The town's market square is surrounded by such historic buildings as the county hall (1723–40) and the King's Head Inn (15th century). The 15th-century grammar school is now part of the County Museum. Aylesbury serves as the county town (seat) of Buckinghamshire. Pop. (2001) 69,021.