Dan Brown sees few visitors in summer as park ranger of Florence’s McFarland State Historic Park. Most people just don’t head south when temperatures soar.

“People go north,” Mr. Brown says. “You know, where the wildfires are.”

At the back door of the east Phoenix area — hardly rural desert anymore — is a historic cornerstone bearing the name of Arizona’s park system founder. McFarland State Historic Park, named for governor, U.S. senator and Arizona Supreme Court Chief Justice Ernest W. McFarland, houses regional exhibits and provides insight into pre-statehood desert architecture. It is one of 29 parks in the Arizona state park system.

Usually, though, it’s October by the time travelers find their way onto the wooden plank porch surrounding the seven-room adobe structure. Walls 24 inches thick and ceilings more than 16 feet high hint of a different Arizona, one before air conditioning, asphalt and Anglo invaders.

“Adobe was all they had to work with,” Mr. Brown explains of the 1878 construction. He points to nails holding mud bricks in place and straw binding water and soil together. “Most of the buildings in town are adobe, too.”

Originally built as a courthouse, the structure was once the center of town activities. Officially, court was held there every month except August, when the heat was unbearable. Unofficially, the courtroom also served as Florence’s social center.

When a bigger courthouse was built in Florence in 1891, the old structure became a hospital. Porches were added and adobe plastered over. From 1891 until 1939 it served the county’s health needs, and today many rooms bear witness of those years with period medical equipment scattered throughout. Following its hospital tenure, the building became a health and welfare center, then county museum. By 1974, when Mr. McFarland bought the property and donated it to the state, it had fallen into disrepair. It would take five years to restore, opening to the public in 1979.

“We still have people come back whose mothers had babies here or who worked in the hospital,” Mr. Brown says.

Others have returned, too. German prisoners of war incarcerated near Florence from 1942 to 1946 have found their way back to the desert. All told, 13,000 German soldiers once lived in a makeshift camp over the four-year period. Some of those prisoners picked cotton and returned in the 1990s to visit farmers upon whose land they earned 80 cents a day.

Uniforms, pictures and a video documenting the return of these prisoners can be found in a park room. —