Oak Tower, Kansas City

Oak Tower, also called the Bell Telephone Building, is a 28-story skyscraper in Downtown Kansas City. The tower was originally 14 stories (185 feet), without any set-backs, but the fast-growing telephone company soon required more space. An addition completed in 1929 doubled the tower's height and made it the tallest building in Missouri until the Kansas City Power & Light Building surpassed it in 1931. Oak Tower's top half was built with Haydite, the first modern structural lightweight concrete, which had recently been invented. The tower's 1929 expansion was the first major project to use the new building material, and it allowed the addition of fourteen new stories, six more than would have been possible using conventional concrete.