Ciudad Perdida (translation: "Lost City") or B200 (Site number 200 of the Buritaca Valley) is the archaeological site of an ancient city in Sierra Nevada, Colombia. An archaeological site is a place (or group of physical sites) in which evidence of past activity is preserved (either prehistoric or historic or contemporary), and which has been investigated using the discipline of archaeology. ... The Sierra Nevada de Santa Marta is a mountain range in northern Colombia. ...

A town (about 13 hectares according to published maps)is one of the best know Tairona nucleated villages and archaeological sites known as Ciudad Perdida (Spanish for "Lost City"). Currently under the care of the Colombian Institue of Anthropology and History it is still a subject of study by colombian archaeologists. Recent demographic studies suggest that "Ciudad Perdida" has inhabited by approximately 1500 to 2000 people that lived in at least 11,700 square meters of roofed space in 184 round houses built on top of stone paved terraces. Population densities are estimated between 80 and 180 people per hectare which is an extremely high population density when compared to most archaeological area of Colombia.

Ciudad Perdida was discovered in 1972, when a group of local treasure looters found a series of stone steps rising up the mountainside and followed them to an abandoned city which they named "Green Hell." When gold figurines and ceramic urns from this city began to appear in the local black market, authorities revealed the site in 1975. During the 1970's and 1980's the site was extensively excavated and restored by colombian archaeologists of the Instituto Colombiano de Antropologia (ICANH)

There appear to be two groups of terraces and house rings, one composed of large structures that may have not been “normal” family units, but rather larger perhaps public or chiefly houses, and another that are likely to have been common residences. The two peaked distribution of B200 is a fairly strong indicator of two broad classes of structures, possibly the result of the existence of some form of social differentiation and public spaces. Some of the structures appear to be extremely large residences or communal houses; two are avoe 500 square meters and are classified by most as open public spaces or “plazas”. The group with exceptionally large houses has only 6 structures that have areas of or above 150 square meters, the average of this group is 135 square meters with a maximum area of 311 square meters, which strongly suggests it is not the usual Tairona residence which have a range between 28 and 75 square meters.

As of 2005, tourist treks are operational again. For a 6 day return trek to the lost city, the cost is approx.. 150 USD. This includes one night staying at the lost city. The trek is about 40 km of walking in total, and requires a good level of fitness.