Pura Ulun Danu Batur (also known as "Pura Ulun Danu," "Pura Batur" or "Pura Bat") is the second most important temple in Bali, after Pura Besakih. Built in 1926, the temple is dedicated to Dewi Danu, goddess of lakes and rivers. "Ulun Danu" literally translates as "head of the lake". 

Originally, Pura Batur and the village of Batur were located down in the caldera at the foot of Mount Batur, an active volcano. A violent eruption in 1926 destroyed both the village and the temple, except for the most important shrine, an 11-tiered meru dedicated to Dewi Danu. The villagers moved to the highest and oldest rim of the caldera, where they rebuilt their village and the temple.

Pura Batur comprises nine different temples, containing in total 285 shrines and pavilions dedicated to the gods and goddesses of water, agriculture, holy springs, art, crafts, and more. Pura Penataran Agung Batur, the principal temple, has five main courtyards. Its most dominant shrines are the 11-tiered meru situated in the inner and most sacred courtyard, three 9-tiered merus dedicated to Mount Batur, Mount Abang, and Ida Batara Dalem Waturenggong, the deified king of the Gelgel dynasty who ruled from 1460 to 1550. The eight other temples are Penataran Pura Jati, Pura Tirta Bungkah, Pura Taman Sari, Pura Tirta Mas Mampeh, Pura Sampian Wangi, Pura Gunarali, Pura Padang Sila, and Pura Tuluk Biyu.