Pacbitun is a Maya archaeological site located near the town of San Ignacio, Belize, in the Cayo District of west central Belize. The modern Maya name given to the site means “stone set in earth”, likely a reference to multiple fragments of stone monuments. The site, at about 240 m above sea level, is one of the earliest known from the southern Maya Lowlands, and was inhabited for almost 2000 years, from ca. 900 BCE to 900 CE. Strategically, it straddles a territory of rolling, hilly terrain between the Mountain Pine Ridge and the tropical forest covered lowlands of the Upper Belize River Valley. Site, architecture, monuments, and nearby caves The central part (Epicenter and Core Zone) of the site lies atop a partly artificial, east-west acropolis of limestone, and is marked today by over 40 masonry structures surrounding five major plazas. Monumental architecture at the site includes multiple temple-pyramids, up to 12 m tall, including an E-Group (Eastern Shrine) architectural assemblage on Plaza A. The palaces of the royal court of Pacbitun are concentrated on Plazas B and C, while an early ceremonial ballcourt is located in Plaza E. The site has multiple elevated causeways (sacbeob) which radiate outward to monumental architectural complexes, including a terminus complex (Structure 10) at the end of the Mai Sacbe. Another causeway (Tzib Sacbe) runs as much as 1 km from the site center. The fragmentary remains of at least 20 monuments (13 stelae and 7 altars, to date) are mostly plain (and perhaps originally painted), with two carved monuments bearing partial hieroglyphic texts. Stela 6, found badly shattered atop Plaza A, has been reconstructed. It depicts a seated Maya ruler, with a Long Count date of 9.2.10.0.0 (March 22, 485 CE), one of the earliest monuments from the eastern Lowlands. A carved fragment of Altar 3 bears the lower half of an ornately dressed, human figure standing atop two hieroglyphs. One of these may represent the Pacbitun toponym of “Sky Cave”, which also occurs on a Late Classic carved slate monument (Stela 21) at the larger center of Caracol, about 50 km to the south. A number of subterranean, limestone caves, virtually all showing signs of ancient Maya use, have been identified in the Pacbitun Periphery Zone. The caves and other karst features (rockshelters, bedrock outcrops, etc.) investigated in the Pacbitun region were used utilized by the Late Preclassic-Early Classic period and