Petroleum Building: Another Early Mayo Project

In 1921, four years after the Mayo brothers finished expanding their Mayo Building at 420 S. Main St., they began a new project at 420 S. Boulder Ave. which was named the Petroleum Building because most of its early tenants were associated with the petroleum industry. The brothers moved their furniture store to the ground floor where it remained until it closed in the 1970s. Cass Mayo opened a suite of offices in the Petroleum Building which he maintained until his death years later.
In this pre-art deco construction boom period, the building was a modest, classical beaux arts design. The main street facades at Boulder Avenue and 5th Street were faced in buff brick while alley exposures featured less expensive painted red brick. Structurally the building’s 10-story frame was reinforced concrete. The building’s base begins with a gray granite wainscot and accent trim across its elevations is also gray. The original double hung steel windows have frames painted a pale yellow/beige color.
Horizontal stone banding occurs at the second and eighth floors. These balance the verticality of a grid of paired windows at 5th Street set off by brick piers. Cartouches below a stylized Maltese cross above the eighth floor and simpler similar details at the second floor soften the building’s straight lines. A heavy stone band occurs directly above the mezzanine setting off the main floor. A massive stone cornice tops the building above a framework of projecting beams architects call modillions. The cornice includes a band of dentils and a series of intaglio circles and rectangular medallions.
At street level there are two canopied entrances at 5th Street and Boulder Avenue. One serves the elevator lobby while the other was the entrance to Mayo Furnishings. There are 12 store fronts glazed with contemporary bronze glass with narrow bronze patterned spandrels identifying a mezzanine. The south façade with nine bays horizontally contains nine window pairs. At the east façade, the horizontal window spacing has a pattern of a pair, a triple, a triple, and a pair.
In 1982, the building received National Register designation. Its occupancy is a combination of residential and office use. The exterior appears to be in pristine condition, well maintained.