The grounds are open dawn to dusk year-round; the visitor center is open Monday through Friday 9:00 a.m. to 4:00 p.m., Saturday 10:00 a.m. to 4:00 p.m., and Sunday noon to 4:00 p.m. Free walking tours on selected dates.Fun with the Family Harvard University established the 265-acre Arnold Arboretum in 1872, the first in the country. Designed by Frederick Law Olmsted, the arboretum specializes in trees, shrubbery, and vines displayed in a beautiful parklike setting. Two peak visitation times are spring, when everything is in bloom and the air is heady with the aroma of budding trees and plants, and autumn, for the vibrant colors. Passive recreational activities that are allowed on the property are cross-country skiing, snowshoeing (no groomed trails), walking, jogging, in-line skating, and biking (biking and skating on paved paths only). Dogs on a leash are allowed, but you are requested to pick up after them. To keep the arboretum pristine, no picnicking or food is allowed on the grounds. Come prepared with sunscreen in the warmweather months as well as bug repellent for twilight. Family activities are ongoing throughout the year.