16.5117°N, 90.0611°W.
Seibal, also written Ceibal, is a Maya city on the west bank of the Pasion River in the Peten, Guatemala, with occupation extending from approximately 1000 BCE through 950 CE. The site has produced the earliest known E-Group ceremonial complex in the Maya lowlands, dated through ceramics and AMS radiocarbon to roughly 950 BCE, which Takeshi Inomata's project published beginning in 2013 and which significantly revised the chronology of early monumental Maya construction. Seibal was sacked and reorganized by Dos Pilas in 735 CE and entered a final florescence in the Terminal Classic, when its rulers — possibly drawing on Putun Maya ties to the Gulf coast — erected a series of stelae with hieroglyphic dates between 849 and 889 CE recording the last functioning Maya long count ceremonies in the region. The site was originally explored by Maler and Tozzer for the Peabody Museum in the 1890s.
The round structure C-79 in the central plaza is a regional rarity in stone Maya architecture.