original otis elevator push button lobby elevator plaque salvaged from mather tower (1928) during interior renovations. the nicely aged cast bronze push button plaque was likely fabricated by or for the otis elevator company. 

mather tower (later lincoln tower, as designated on the michigan–wacker historic district roster; now identified primarily by its address) is a neo-gothic, terra cotta-clad high-rise structure in chicago, ills.  

the 521 ft. building is sometimes called "the inverted spyglass" by chicagoans due to its highly unusual design, an 18-story octagonal tower atop a more conventional 24-story rectangular "box." briefly the tallest building in chicago at the time of its completion in 1928, it remains the city's most slender high-rise structure at only 100 by 65 feet at its base. the interior space within the upper octagonal spire contains the least square footage per floor of any chicago skyscraper.

it was designed by herbert hugh riddle (1875–1939), the architect of the chicago theological seminary, as headquarters for the mather stock car company, a builder of rail cars for transporting livestock. its design was greatly influenced by the pioneering chicago zoning ordinance of 1923, which placed no limit on the height of new buildings as long as the surface area of the structure's uppermost floor did not exceed 25% of its footprint. this resulted in a multitude of tall, slender, "setback" towers, of which the mather is an extreme and unusual example. the top floor of the octagonal spire has only 280 square feet of floor space.

mather company's founder, alonzo mather (a descendant of cotton mather) is said to be responsible for a number of the building's distinctive design features, including the octagonal tower. initial plans called for construction of a second, identical building on north michigan avenue, behind the mather and connected to it by a ground-floor arcade, but onset of the great depression in 1929 forced its cancellation.