The Eagle Gate is an arch across State Street at its intersection with South Temple. It honors Brigham Young's 1859 gate, which was an entrance to his property and the City Creek Canyon road. The tolls for hauling wood from the canyon could be paid by giving Young every fifth load.
After the road was opened to the public and the gates removed, the arch with its eagle and beehive stayed. The structure has been rebuilt twice, in the 1890s and the 1960s.
The current bronze eagle was made in the early 1960s and has a wingspan of 20 feet. It weighs 4,000 pounds. The arches and pillars are a steel frame covered in metal panels, and Wikipedia calls the design one of the city's finest examples of mid-century modern.