A long avenue leads to the "Pyramid of the Moon" and it is sometime thought that this avenue might have been filled with water to make a sort of canal or waterway approaching the pyramid.
Pyramid of the Moon, Teotihuacán
Pyramids in the New World, such as the Pyramid of the Moon at Teotihuacán shown above, are unlike those in Egypt in that, rather than coming to a peak, they are level atop, forming platforms for temples. American pyramids often achieved their monumental proportions because their builders, rather than starting from scratch, would envelope old structures as fill. The Cholula pyramid, with a volume of 3 million meters, a base covering 46 acres, and a height of 198 feet, has been said to be the largest preindustrial building ever erected on earth. Yet its final bulk was achieved by various building projects over the centuries that incorporated earlier pyramids—larger than the Pyramid of the Moon. Like their Egyptian counterparts, however, the pyramids sometimes contain royal tombs painted with murals and accompanied with precious jades and, in the Post-classic period, gold ornaments. Although many have speculated about burials inside Teotihuacán’s Sun and Moon pyramids, the first evidence suggestive of a royal tomb in the Pyramid of the Moon was discovered only in 2002.
The Pyramid of the Moon is the second largest building in Teotihuacan after the Pyramid of the Sun. The Pyramid of the Moon is located in the northern part of Teotihuacan and it mimics the contours of Cerro Gordo. Some have called it Tenan which in Nahuatl means "mother or protective stone." The Pyramid of the Moon covers a structure older than the Pyramid of the Sun which existed prior to 200 A. D.
The Pyramid's construction between 200 and 450 A.D. completed the bilateral symmetry of the temple complex. A slope in front of the staircase gives access to the Avenue of the Dead, a platform atop the pyramid was used to conduct ceremonies in honor of Chalchiuhtlicue, the goddess of water and of the moon. This platform and the sculpture found at the pyramid's bottom are thus dedicated to Chalchiuhtlicue.
Opposite Chalchiuhtlicue's altar is the Plaza of the Moon. The Plaza contains a central altar and an original construction with internal divisions, consisting of four rectangular and diagonal bodies that formed what is known as the "Teotihuacan Cross."
Between 100 and 500 A.D, an ancient people built a flourishing metropolis called Teotihuacan on a plateau about 25 miles (40 km) from present-day Mexico City. With its accurately aligned avenues and a huge plaza surrounded by 15 monumental pyramids, Teotihuacan was bigger than any city in Europe at that time. It covered over nearly 8 square miles (21 km2) and 200,000 people lived there. Teotihuacan was built 700 years before the Aztecs began constructing their capital city of Tenochtitlan.
It was said by the Aztecs to have been surmounted by a huge stone figure related to the moon but this figure was uncovered (weighing 22 tonnes and was somehow lifted to the top of the pyramid) and it is thought more likely that it represents a water deity. 
Recently, archaeologists have excavated beneath the Pyramid of the Moon. The archaeologists are looking for clues to the history of this mysterious culture. Tunnels dug into the structure have revealed that the Teotihuacan’s citizens did not remain pleased with their architectural feats for very long. Over a period of several hundred years, the pyramid underwent at least six facelifts and each new addition was larger and covered the previous structure.
As the archeologists burrowed through the layers of the pyramid, they discovered artifacts that provide the beginning of a timeline to the history of Teotihuacan. The latest find, made by a team led by Saburo Sugiyama, associate professor at Aichi Prefectural University in Japan and adjunct faculty at Arizona State University, and Ruben Cabrera of Mexico’s National Institute of Anthropology and History, is a tomb apparently made to dedicate the fifth phase of construction. It contains four human skeletons, animal bones, jewelry, obsidian blades, and a wide variety of other offerings. Archeologists estimated that the burial occurred between 100 and 200 A.D.
Another tomb dedicated to Chalchiutlicue was discovered a year ago. It is dated to the fourth stage of construction. It contained a single human male sacrificial victim as well as a wolf, jaguar, puma, serpent, bird skeletons, and more than 400 other relics which include a large greenstone and obsidian figurines, ceremonial knives, and spear points.
ScienceDaily (1999-09-21) -- An unexpected set of new discoveries in the ongoing excavation beneath the Pyramid of the Moon at Teotihuacan may provide critical clues in reconstructing a 2,000-year old history still mysteriously missing from the ruins of the ancient master-planned metropolis, located 25 miles from current Mexico City.