Xultún is a large Maya archaeological site located 40 km northeast of Tikal and 8 km south of the smaller Preclassic site of San Bartolo in northern Guatemala. The site, which once supported a considerable population, has a 35 m tall pyramid, two ballcourts, 24 stelae (the last of which, Stele 10, dates to 889), several plazas, and five large water reservoirs (aguadas). Incompletely charted in the 1970s, it is the largest-known Classic Maya site that has yet to be archaeologically investigated. Nearby sites include Chaj K’e’k Cué, believed to be the residential area of the Xultún elite; Isla Oasis; and Las Minas. The latter sites contain large limestone quarries. Proyecto Regional Arqueológico San Bartolo-Xultun (English: San Bartolo-Xultun Regional Archaeological Project) (PRASBX) has been investigating this site and the nearby site of San Bartolo since 2001. The project currently (as of 2022) operates under the directorship of Dr. Heather Hurst and Boris Beltrán. Since 2008, excavations in Xultun have revealed several unusual features. One of the unusual features is a Late-Classic room (labeled 10K2) with murals on three sides, showing three dark seated characters with large mitres signalling their priestly function (west wall); a kneeling official extending a stylus to the seated king, Yax We'nel Chan K'inich (north wall); and three other characters, together with unique Maya calendar notations chiefly relating to lunar astrology (northeast and east walls). Most of the characters bear hieroglyphic titles, some of these reminiscent of the senior-junior rankings of the traditionalist Maya civil-religious hierarchy. The lunar notations strongly recall much later calculations found in the Dresden Codex. Another important feature, described by William Saturno in a 2014 presentation, is a building complex called 'Los Árboles', dating to the Early Classic. Its front is decorated with complicated stucco imagery relating to the royal cult of the jaguar, also in evidence on several of the site's stelas.