Located in the Verde Valley of the central part of the U.S. state of Arizona, Montezuma Castle is one of the best-preserved prehistoric structures in North America. It is not actually a castle, but a pre-Columbian Pueblo Indian cliff dwelling. It was named by early European settlers, who incorrectly thought the structure was related to the Aztec emperor Montezuma II (1470-1520). It was actually built by the Sinagua (Spanish for “without water”) people between 1100 and 1300, long before Montezuma was even born.

People lived as hunters and gatherers in the Verde Valley for thousands of years. Two neighboring cultures— the Hohokam in the south and the Northern Sinagua in the north—are credited with making advances in agriculture and architecture.

Between 700 and 900 C.E., some Hohokam moved north into the Verde Valley. They were skilled farmers, and they grew crops using a variety of techniques, including canal irrigation. Their dwellings were one-room pit houses, dug partially into the ground on terraces to overlook their fields.

Above-ground masonry dwellings—buildings made out of rock—are attributed to the influence of the Northern Sinagua. Their culture was centered near present-day Flagstaff, Arizona. The Northern Sinagua began to migrate to Verde Valley around 1125.

By 1150, large pueblos, often on hilltops or in cliffs, were being built by the Southern Sinagua. A pueblo is basically a Native American apartment complex, with many residences and central areas all enclosed in one building. Pueblos are often several stories tall and accessed by ladders. Montezuma Castle and Tuzigoot, about 32.2 kilometers (20 miles) northwest of Montezuma Castle, are both multistory pueblos.

Montezuma Castle

Montezuma Castle is located along Beaver Creek, a small but reliable water source running through the canyon. The Castle was built into a limestone cliff about 24 meters (80 feet) above the valley floor. This conserved precious farmland near the water and offered security.

“There is little evidence of conflict or warfare, but perhaps people felt more secure living in the Castle,” says Anne Worthington, National Park Guide at Montezuma Castle National Monument. “A small ruin above the Castle, on the top of the cliff, allows views of the entire countryside. A sentry would have advance warning of anyone entering the area.”

With five levels and 20 rooms, the Castle could have housed 35 to 50 people. The primary entrance is through a doorway on the second level. Wooden ladders extended through openings in the ceilings and floors provided access to other levels. The walls are made of limestone rocks from the local area. These were stacked and held together with clay, much like bricks are laid today. Adobe was used to coat and seal the outer walls. Although different materials are now used, modern homebuilders still use the same methods.

Most of the rooms in the Castle were built on natural ledges. Where ledges were unavailable, the Sinagua built floors. They used large support beams of sycamore wood and cross beams made of dry branches, twigs, grasses, and reeds. Several inches of mud completed both the ceiling and the floor for the next level. Mud construction was ideal for the desert climate. It was cool in the summer and conserved heat in the winter.

Around the corner from Montezuma Castle is a larger structure named "Castle A" by the archaeologists who excavated it in 1933. It had 45–50 rooms and could have housed about 100 people. Although it is about twice the size of Montezuma Castle, it is not as well preserved because a fire around the year 1400 destroyed most of the interior. Today, all that can be seen are some collapsed walls and a partially rebuilt foundation.

Montezuma Well

Montezuma Well, a unit of Montezuma Castle, is located 17.7 kilometers (11 miles) to the northeast. It is a natural sinkhole formed 11,000 years ago by the collapse of a limestone cavern. Measuring 112.2 meters (368 feet) wide, it is 16.8 meters (55 feet) deep. It is surrounded by cliffs that are 21.3 meters (70 feet) high.

Montezuma Well is fed by three or four underwater vents, or fissures. The fissures for the well reach depths of 36.6 to 42.7 meters (120 to 140 feet). Each day, 5.7 million liters (1.5 million gallons) of water flow into the well at a constant temperature of 23.3 degrees Celsius (71.4 degrees Fahrenheit).

“Scientists have not discovered the origin of the consistently warm water that feeds Montezuma Well,” says National Park Ranger Rex Vanderford. “They have noted the flow rate from the well rarely fluctuates—but the source deep in the Earth’s layers remains a mystery,”

Despite the presence of oxygen in the water, Montezuma Well contains no fish. This is because of extremely high levels of carbon dioxide collected by the water as it passes through limestone. Fish cannot live in an environment with so much carbon dioxide. An isolated and unique ecosystem, Montezuma Well has allowed amphipods—small, shrimp-like animals—and leeches that feed on them to evolve into species that cannot be found anywhere else on the planet.

Montezuma Well was used as a resting spot by wildlife and nomadic tribes for more than 9,000 years. However, there were no permanent settlements there until 1,400 years ago, when agriculture was introduced. The first residents built an irrigation ditch from the well to water their crops.

Eventually, the well supported a thriving community of up to 200 people. They built cliff dwellings along the well’s rim and pueblos on the hilltops. They also expanded the original irrigation ditch in order to help grow enough food for everyone. Today, water still exits the well through a 91.4-meter (300-foot) cave into this irrigation ditch.

The Sinagua People

The Sinagua lived principally by farming, but supplemented their staple crops by hunting, gathering, and trading. Their diet relied heavily on corn, which they augmented with game including deer, antelope, rabbit, bear, muskrat (Ondatra zibethicus), and duck.

The Sinagua also mined a nearby salt deposit. Evidence shows that salt was widely traded throughout the region.

Talented artisans, the Sinagua fashioned stone tools, such as axes, hammers, and corn grinders. They crafted awls (pointed instruments for piercing holes) and needles from bones. They made garments of cotton and personal ornaments of shell, turquoise, and argillite (a local red stone). They also created highly polished reddish-brown pottery.

Montezuma Castle and Well reached their maximum size in the 1300s. By the early 1400s, the Sinagua abandoned the sites and their culture dissolved. Possible explanations for the abandonment of Montezuma Castle include drought, disease, overpopulation, depletion of natural resources leading to crop failure, and conflicts within and between groups.

The Sinagua probably joined relatives in large pueblos to the north and east. Their modern descendants include the Hopi, Yavapai, and six other affiliated tribes. The Hopi believe that “it was a migration of their ancestors, preordained to fulfill a covenant with one of their most important spiritual beings, and they stress the fact that they did not disappear,” Worthington states. “They are still very much here.”

In the late 1800s, Montezuma Castle became a popular tourist site for soldiers, stationed at nearby Fort Verde, and settlers. Some saw it as a site to preserve while others treated it like a treasure chest. Visitors were able to climb a series of three ladders and enter the dwelling until 1951. That same year, Interstate 17 was completed and visitation skyrocketed. Due to concerns for both visitor safety and the structure, the ladders were removed.

Montezuma Castle National Monument only allows park rangers and other personnel to enter the Castle. They monitor the site to make sure it is structurally sound and no material is stolen or damaged.