The largest book (in a poti-format), and perhaps also the biggest book ever in the world, is the one called “Po-ti-lcags-lung-ma” (lit. “The Poti with Iron Cord”) in Sa-skya Monastery in Tibet. For a description, see the Ri mo’i rnam gzhag (pp. 507, 94). The manuscript is that of the Aṣṭasāhasrikā, and is made from precious materials such as gold, silver, turquoise. The colophon of the manuscript is said to mention that it was commissioned/made by ’Phags-pa, an emanation of (Bodhisattva) Samantabhadra, and that it is the “support of personal practice” (thugs dam rten) of the successive (Sa-skya) patriarchs (gong ma rim byon rnams).