Tikal, or Yax Mutal, was an important city in the empire of the Maya from 200 to 900 A.D. ... Tourism has been credited with providing the funds to restore and maintain the Tikal, and a museum has been open there since 1964.New research suggests mercury and toxic algae poisoned the settlement's reservoirs. In the ninth century A.D., the Maya abandoned the great city of Tikal after hundreds of years of prosperity and expansion. ... As the researchers argue, this system inadvertently contributed to the city's undoing.