There are seven high-priority "A Lawns", collectively covering 65 acres (26 ha), that are heavily used: Sheep Meadow, Great Lawn, North Meadow, East Meadow, Conservatory Garden, Heckscher Ballfields, and the Lawn Bowling and Croquet Greens near Sheep Meadow. These are permanently surrounded by fences, are constantly maintained, and are closed during the off-season. Another 16 lawns, covering 37 acres (15 ha), are classed as "B Lawns" and are fenced off only during off-seasons, while an additional 69 acres (28 ha) are "C Lawns" and are only occasionally fenced off.