The monastic complex of Alchi is undoubtedly one of the most important and fascinating monuments preserved in the Himalayas. With its earliest monuments dating from the late twelfth to the mid-thirteenth centuries, it provides unique insight into the Buddhist culture flourishing at that time. Through a detailed analysis of the architecture, sculptures and murals in their context, their interrelationship to each other and to Tibetan textual sources likely known at the time the publication offers a deeper understanding of the monuments religious environment. A reassessment of some of the inscriptions preserved at the site provides new insights into the historical circumstances of the temples construction. This publication builds on and includes an updated version of the Sumtsek book by Roger Goepper, covers all early remains of the Alchi Choskhor, and still relies on the quality of Jaroslav Poncar’s early documentation for all main monuments. Holger Neuwirth and Carmen Auer contributed on the architecture and all plans, and Rob Linrothe and Nils Martin contributed new studies on the lineage and foundation inscription of the Sumtsek respectively.