Seibal, known as El Ceibal in Spanish, is a Classic Period archaeological site of the Maya civilization located in the northern Petén Department of Guatemala. It was the largest city in the Pasión River region.
The site was occupied from the Preclassic Period through to the Terminal Classic, with a significant hiatus. The principal phase of occupation dates to the Late Preclassic (400 BC – AD 200), followed by a decline in the Early Classic (AD 200–600). Seibal experienced a significant recovery in the Terminal Classic immediately prior to its complete abandonment, reaching its second peak from about 830 to 890, with a population estimated at 8–10,000 people. The dates on the stelae at Seibal are unusually late, with monuments still being dedicated after the Classic Maya collapse had engulfed most of the Petén region. Many of Seibal's late monuments show artistic influence from central Mexico and from the Gulf Coast of Mexico.
Seibal is located on bluffs about 100 metres (330 ft) above the Pasión River, a major tributary of the Usumacinta River. About 100 kilometres (62 mi) downstream, the Pasión River joins with the Salinas River to form the Usumacinta, which flows northwards to the Gulf of Mexico. The site lies in the Petén department of northern Guatemala, 16 kilometres (9.9 mi) east of the modern town of Sayaxché. Seibal lay 27 kilometres (17 mi) east of the Late Classic city of Dos Pilas and 100 kilometres (62 mi) south of Tikal. Lake Petén Itzá lies 60 kilometres (37 mi) to the north of the ruins.
Seibal lies among tropical rainforest on a limestone plain that is intermittently hilly and flat.
Seibal is a medium-sized site. The site core is divided into three principal hilltop groups (Groups A, C and D) connected by causeways and covers a little over 1 km². The causeways were faced with masonry and had parapets in places. Causeway I is the western causeway, Causeway II is the south causeway and Causeway III is the eastern causeway. Group D is a fortress refuge concealed above the river frontage. Group B is a small complex located about 3 kilometres (1.9 mi) from the site core. Group A is smaller than Group D but has most of the sculptured monuments. Various small housemound groups lie beyond the site core. They are spaced between 50 and 100 metres (55 and 110 yd) apart, extending for several kilometers to the north, south and west.
Only two structures have been restored at Seibal, the A-3 temple platform and the C-79 circular platform. Both were restored during the investigations carried out by the Peabody Museum in the 1960s.
Seibal possesses a satellite site located to the north, known as El Anonal. This site has large structures built from clay that date to the Middle Preclassic period.