Almost everything here is outside and seasonal: the valley behind town, a gondola from the middle of the pedestrian core, and two mining ghost towns, with one free art museum for the days the weather turns.
Maroon Bells Scenic Area
Reservations are required May to October: the RFTA shuttle from the Maroon Bells Welcome Center at Aspen Highlands (75 Boomerang Road) costs 16 USD adults and 10 USD for under-12s and over-65s, about 15 minutes each way, or 10 USD per vehicle for a trailhead parking slot before 7am or after 5pm. The county road normally closes from about 15 November to late May.
Silver Queen Gondola, Aspen Mountain
The gondola leaves from the bottom of the mountain at the edge of the pedestrian downtown and runs in both winter and summer; in summer the top opens for hiking, on-mountain dining, yoga and nature programmes. Check the operating calendar, as it shuts between seasons.
Aspen Art Museum
Free to enter at 637 East Hyman Avenue, open Tuesday to Sunday 10am to 6pm and closed Mondays, with a rooftop cafe. It is a contemporary kunsthalle with no permanent collection, so what is on changes completely between visits.
Aspen Center for Environmental Studies, Hallam Lake
A nature preserve and education centre a short walk from downtown, open Monday to Saturday 9am to 5pm, running naturalist-guided walks, birding outings and family programmes. ACES also runs Rock Bottom Ranch down-valley and the Toklat centre up Castle Creek.
Ashcroft and Independence ghost towns
Two 1880s silver-mining settlements kept by the Aspen Historical Society: Ashcroft at 11000 Castle Creek Road, and Independence 16 miles east of town on Highway 82 near the pass. Independence is only reachable when Independence Pass is open, which is roughly late May to early November.