A HOLOCENE RESEARCH REPORT Abstract: The ninth-century world-heritage Buddhist monument of Borobudur (Java, Indonesia) stands above the floor of a dried-out palaeolake, but it remains uncertain as to whether it was ever constructed on a lake shore. Here we reveal through new chronological and palaeoenvironmental data on the extant sediment record of the area that Borobudur intentionally stood by an existing lake. For the first time, evidence of this conjunction validates quite literally the debated cosmological interpretation of the edifice as an aquatic lotus symbol upon which Buddha is seated. The fluctuating life history of the lake spanned at least 20000 years.