Tempe will celebrate Monday the 90th anniversary of the dedication of the Old Mill Avenue Bridge and honor the man who was responsible for creating the city landmark.

A short ceremony honoring Ralph Hoffman and the bridge will take place 11 a.m. May 1 on the front patio of the Hayden House, 1 W. Rio Salado Parkway.

After the ceremony, Tempe Historic Preservation Officer Zachary Lechner will lead people on a walk to the bridge where a plaque honoring Hoffman is being installed.

Hoffman served as the Arizona state bridge engineer from 1923 to 1954. He designed the Old Mill Avenue Bridge, the Navajo Bridge at Marble Canyon, the original Pinto Creek Bridge and others around the state, according to a city release.

“The Old Mill Avenue Bridge is a showcase for Hoffman’s talent,” the release stated. “Thanks to Hoffman’s solid design, while other Salt River bridges failed during floods, the Mill Avenue Bridge survived.

“Its beauty and longevity have made it a beloved Tempe icon.”

“I can’t imagine what Tempe would be like today had the Mill Avenue Bridge not been built,” Mayor Corey Woods said. “Like the Hayden Flour Mill and the Hayden House, the bridge is a touchstone to our past.”

The Old Mill Avenue Bridge is listed in the National Register of Historic Places and the Tempe Historic Property Register.

The bridge is significant for both its method of construction and its artistic design, according to the release. It is a poured concrete structure with 10 arched spans and measures 1,577 feet, including approach roadways.

It cost $518,788 - more than $10 million in today’s dollars - to build, the release stated.