Generations have come to know the concrete outside of the Hayden Flour Mill without appreciating the arguably more interesting milling equipment inside it or a stone arch hidden beneath it.
But a redevelopment will begin in June to restore the iconic mill - and to reveal rarely seen equipment and stonework that's been out of view for most of the last century.
Tempe-based Avenue Communities unveiled plans Tuesday, pledging to start work that Tempe and other developers have failed to get under way since talks began in 1990. Avenue expects it will take 14 to 15 months to restore the mill, add a glass-and-steel structure beside it and open about six restaurants, bars and boutiques.
A stone arch and waterway will become an entrance after spending decades under dirt - hidden so long that many feared the 1890s-era stonework had been destroyed. But as archaeologists explored the site in the past year to look for relics from Hohokam and European settlers, they discovered that stonework was undamaged since its burial in the 1920s.
"This was a complete and absolute surprise," Tempe Mayor Hugh Hallman said.
Hallman has made historic preservation a top priority and gave tours of the site Tuesday. With him was Ken Losch, a principal of Avenue Communities who said the old arch will help create a sense of place that's rare in the Valley. He stood in the arch and cited it as one of the mill's most intriguing features.
The restoration will let visitors see how water powered the mill, flowing through a canal, under the arch and in a stone-lined channel. The mill opened in 1874, built by Tempe founder Charles Trumbull Hayden. After a fire destroyed the mill, he rebuilt a second one in 1891, which is when the arch was built. A second fire destroyed that mill, which was replaced with a concrete building in 1918.
Water powered the mill through the mid-1920s.
The mill was the longest continuously operating industrial business in Arizona when it closed in 1998.
Losch originally planned to display the milling equipment in a glass enclosure next to the building, but said he's had to change plans. He will display it somehow, but not until he starts a second phase to turn the 1950s-era silos into a boutique hotel.
Archaeologists also found a major Hohokam canal at the southeast corner of Mill Avenue and Rio Salado Parkway. It's unclear if that will be displayed. Though exposing the canal would show the area's rich history, Hallman said it could distract from the rest of the project.
Avenue will later build 500,000 square feet of offices, condos and shops on the site, though no timeline has been set.
Losch said Avenue will lose money on the first phase, which will cost about $40 million, and will make money only in future phases.