Belton House was built between 1685 and 1688 for Sir John Brownlow, and the Brownlows shaped the Lincolnshire estate for 300 years, later adding a cast-iron conservatory. It holds a world-renowned library, silver, porcelain and a lapis lazuli cabinet, and the Windsor bedroom is kept as it was when the future King Charles III stayed as a Cranwell cadet. Outside are Dutch and Italian gardens, a maze, lakeside pleasure grounds and 1,300 acres of deer park with a white stag among the fallow herd. The outdoor adventure playground is the largest in the National Trust, backed by an indoor play cafe, and dogs on leads are welcome in park and gardens. Reviewers rate the Stables Cafe and the shop among the Trust's best and single out the library, where books are left out to browse. Tips from regulars: bring water for park walks, have membership cards ready at the drive-in admission points, and on Tuesdays and Wednesdays only a quarter of the house is open.