Tikal National Park encompasses 575 square kilometres of jungle and thousands of ruined structures.
The central part of the ancient city alone contains 3,000 buildings and covers about 16 square kilometers.
Tikal is also part of the one-million-hectare Maya Biosphere Reserve created in 1990 to protect the dense forests of the Peten, which started to disappear at an alarming rate due to population pressures, illegal logging and slash-and-burn agricultural practices.
Archeologists estimate that the Maya settled in the area now known as Tikal in about 900 BC.
Tikal grew into an important ceremonial, cultural, and commercial centre over the centuries. Most of the city's huge temples were constructed during the eighth century AD when Tikal became the greatest city in the Maya world with a population of perhaps 100,000.
Like Maya complexes on Mexico's Yucatan Peninsula, Tikal fell into decline at the end of the ninth century and was virtually abandoned. The causes of the Maya empire's collapse remain a mystery, but wars, famine, overpopulation and resource depletion have all been blamed.
Tikal's great stone monuments languished for centuries and were gradually reclaimed by the jungle. Hernan Cortes, the conqueror of Mexico, and his motley band of conquistadors marched by Tikal in 1525, but they failed to see its temples concealed by 40-metre-tall silk, cotton, cedar and mahogany trees.
Spanish friars later wrote of a great city hidden in the forests of the Peten. It wasn't until 1848 that an expedition sent out by the Guatemalan government officially discovered the ruins. Swiss, German and British archeologists soon followed to clear debris and begin studying the site.
The Museum of the University of Pennsylvania and the Guatemalan Institute of Anthropology and History restored Tikal's structures to their current condition during the 1950s and 1960s. UNESCO designated the ruins a World Heritage Site in 1979. Today Tikal is to Guatemala what the Great Pyramids are to Egypt, a national symbol and a source of pride in the past.
Enormous trees still shroud Tikal's buildings, which cluster in groups reached by wide causeways meandering through the tropical forest, home to toucans, parrots, wild turkeys, howler monkeys, raccoon-like coatimundis and countless other creatures. Tikal's grand scale even awes those who have visited spectacular Mayan sites such as Palenque and Chichen Itza in Mexico.
The Temple of the Grand Jaguar (Temple I) and the Temple of the Masks (Temple II) loom like a pair of colossal bookends on opposite sides of the Great Plaza, a vast expanse ringed by terraces, palaces and ball courts.
Temple I rises some 50 meters above the plaza's eastern end. A stone stairway leads up the pyramid's nine tiers, corresponding to the nine levels of the Mayan underworld. Tourists have fallen to their deaths from these vertiginous steps, prompting park authorities to recently ban climbing.
In 1958, archeologists discovered the tomb of Ah Cacau (Lord Chocolate), one of Tikal's greatest rulers, inside Temple I. Ah Cacau's skeleton was festooned with jade ornaments and surrounded by precious offerings, including pottery, alabaster, sea shells and pearls from the Caribbean coast. You can see a replica of this elaborate tomb in the Tikal Museum near the visitors' centre.
Temple I has yielded other treasures, including intricately carved wooden lintels over its doors, which have furnished clues to Maya beliefs and cosmology.
Called Temple of the Masks because of huge stone masks guarding its stairway, Temple II is almost as tall as Temple I, but safer to climb. Its summit offers travel-poster views of the Great Plaza and two labyrinthine ceremonial and residential complexes named the North Acropolis and the Central Acropolis.
Dozens of stone pillars known as stelae, each one paired with a circular altar, stand in rows throughout the plaza and along surrounding terraces. Carvings and glyphs commemorating important dates and the great deeds of Tikal's rulers still adorn many of these weathered monoliths.
From atop Tikal's pyramids, Maya astronomers tracked the movements of Venus and all the other visible planets.
They used these calculations -- extremely accurate even by today's standards -- to fine tune their complex calendar, which can be compared to a system of interlocking gears made up of a 260-day calendar known as the tzolkin that meshed with a 365-day solar calendar to complete 52-year cycles.
The enigmatic Maya ran this complex arrangement like a time machine back and forth across immense spans of time.
One of Tikal's stelae records a mysterious date more than five million years in the past, and glyphs on a stela at Quirigua in eastern Guatemala commemorate some obscure event that took place 400 million years ago.