Ananova:

Scientists have rediscovered the lost Mayan city of Cancuen after working deep in Guatemala's northern jungles but they believe it will take 10 years to fully unearth the city.

The ancient trade centre, which dates to 400BC, is buttressed by a 270,000-square-foot Mayan palace with three 66ft high floors and 170 rooms and is 20 times bigger than the team expected.

The building is among the most grandiose Mayan structures ever discovered, the National Geographic Society, which is sponsoring the excavation project, has announced.

"We started off working with what we thought was a small palace, part of a small Mayan settlement," said Arthur Demerest, a Vanderbilt University archaeologist and head of the Cancuen project.

"What we found was a palace 20 times as large as we were expecting and an important Mayan marketplace that had been forgotten for almost 100 years."

Built in the shadow of the hulking palace, the five-square-mile city featured a crowded rectangular layout of heavy stone walls, 11 spacious stone-tiled patios and buildings with cubbyhole-like rooms and thick, multileveled roofs.

While Demerest said scientists aren't sure how many Mayan merchants traded in Cancuen, the city is thought to have attracted thousands from nearby highland settlements, including the sprawling, majestic city of Tikal, 85 miles to the northeast.

Cancuen, an ancient Maya word meaning "Place of the Serpent," became a key trading post because of the sprawling River Passion in what is known as southern Peten, Guatemala's northernmost province, Demerest said.

First discovered in 1905 by Austrian explorer Tobert Maler, scientists and looters ignored the site for years.

Cancuen remained shrouded by jungle until 1967, when a group of Harvard graduate students returned to the city for less than a week and brought back crude sketches of what they thought was waiting to be discovered there.

Demerest and scientists from Guatemala's City's Valley University were drawn back to the area in April because hieroglyphics inscribed in artifacts recovered in Tikal and Dos Pilas, the ancient Maya's largest commercial center, made reference to a marketplace called Cancuen and its powerful fourth-century BC ruler, Tah Chan Wi, or "Celestial Fire."