Mount Merapi and the cool hill resort of Kaliurang on its lower slopes are the main draws. The Merapi Volcano Museum is a good primer on the geology and human history of the mountain; nearby, the private Ullen Sentalu Museum is the finest collection of Javanese royal-court culture anywhere.
Closer to Yogyakarta city, the pyramidal Yogya Kembali Monument tells the story of the war of independence. Scattered across the regency are a number of small Hindu temples — Candi Gebang and Candi Kimpulan among them — which give a sense of the layered religious past beneath the modern lowland sprawl.
Several villages around Sleman offer village tourism — structured visits where you can join in daily agricultural life. Brayut Village has well-preserved old-style Javanese homes. Candirejo, set between two rivers with volcanoes as a backdrop, is particularly scenic. Sambi Village in the Merapi foothills has a traditional joglo house open for homestays, and Tanjung Village is surrounded by rice fields with a 200-year-old joglo still standing.