The former estate of Holland House, a 17th-century Jacobean mansion that's now home to the capital's best-situated YHA hostel, the park has an authentic aristocratic air, with manicured lawns, flower beds, and a Japanese water garden, complete with huge, colorful carp and a small waterfall. Haughty peacocks patrol the lawns during the day before retiring to the trees to squawk at each other come nightfall. Somewhat surprisingly, for such a well-tended space, the park also has an area of dense woodland at its northern end. The park's ecology center (tel. 020/7938-8186) gives regular free nature-themed talks in summer. There are also facilities for children, including an adventure playground.