The Ingalls Building: The world's first reinforced concrete skyscraper

The Ingalls Building, standing at 6 East 4th Street in Cincinnati, has been a landmark since 1903. Designed by the Cincinnati architectural firm Elzner & Anderson, this 64-meter tall edifice is the world's first reinforced concrete skyscraper. Today, it welcomes guests as the Courtyard by Marriott Cincinnati Downtown, inviting them to experience its history as a daring engineering feat.

The building's construction was an audacious project driven by the system of Ernest L. Ransome, which involved casting twisted steel bars inside concrete slabs as reinforcement. Because concrete has low tensile strength, many believed a tower of this height would collapse under its own weight. To overcome this, engineers used a monolithic concrete box design with eight-inch walls, poured at a rate of three stories per month.

The exterior features a Beaux Arts Classical style with white marble on the first three stories, glazed gray brick on the next eleven, and white terra cotta on the top floor. In 1974, it was designated a National Historic Civil Engineering Landmark and was added to the National Register of Historic Places in 1975. It remains a significant example of the acceptance of concrete in high-rise construction.

Sources: Wikipedia, OpenStreetMap, Wikidata, Wikimedia Commons