The Spanish were the first Europeans to visit the immediate area of the monument. No reference by them to Montezuma Castle has been found; however, in 1583, the Antonio de Espejo Expedition probably visited Montezuma Well. Espejo journeyed from the Hopi Indian villages in northeastern Arizona to the Verde River, traveling down a stream identified as Beaver Creek—thus he had to pass Montezuma Well. A further indication that he passed the Well is found in one of the expedition journals which describes an abandoned pueblo and a ditch running from a nearby pond.

While the Verde Valley was Spanish and Mexican territory, no settlements were established in the immediate vicinity of the monument.

As a result of the war with Mexico (1846-48), the United States acquired the Verde Valley. By 1865, enough settlers had come into the valley to warrant the establishment of Fort Verde near the location of present-day Camp Verde. The earliest date of a pioneer visitor’s scratched inscription in Montezuma Castle is 1880; however, it is known that the ruin was visited by army personnel in the 1860’s. Dr. Edgar A. Mearns, who was assigned to the fort, wrote the first detailed account of Montezuma Castle. It was published in 1890 in the Popular Science Monthly, and described the ruin very much as it is today:

Upon my first visit in 1884, it was evident that nothing more than a superficial examination had ever been made. In 1886 I caused the debris on the floors to be shoveled over. This material consisted of a quantity of dust and broken fragments of pottery and stone implements, together with the accumulation of guano from bats that inhabited the building. This accumulation, in the largest room of the top floor, was 4 feet in depth. As no one had ever disturbed it, the floor was found in exactly the same condition in which it was left by the latest occupants.

A few years later, the first repair work was done. In 1897, members of the Arizona Antiquarian Association visited Montezuma Castle and, with funds raised by subscription, cleaned up the ruin and performed repairs including the installation of ladders, iron anchor rods, and corrugated iron roofs.

On December 8, 1906, by Presidential proclamation, 160 acres were set aside from the public domain to preserve Montezuma Castle as a National Monument. By Presidential proclamation of February 23, 1937, 366 acres were added to the area to give better protection to the monument entrance and to the area in the foreground of the ruin. On April 4, 1947, Montezuma Well was acquired by the Federal Government through purchase from private owners. This last purchase gave the monument a total area of somewhat over 1 square mile.