The Mechanics' Bank and Trust Company Building is an office building located at 612 South Gay Street in Knoxville, Tennessee, United States. Built in 1907 for the Mechanics' Bank and Trust Company, the building now houses offices for several law firms and financial agencies. The building's facade was constructed with locally quarried marble, and is designed in the Second Renaissance Revival style. In 1983, the building was added to the National Register of Historic Places for its architectural significance.

Tennessee marble is a type of crystalline limestone found only in East Tennessee, in the southeastern United States. Long esteemed by architects and builders for its pinkish-gray color and the ease with which it is polished, the stone has been used in the construction of numerous notable buildings and monuments throughout the United States and Canada, including the National Gallery of Art, National Air and Space Museum, and United States Capitol in Washington, D.C., the Minnesota State Capitol, Grand Central Terminal in New York, and Union Station in Toronto. Tennessee marble achieved such popularity in the late-19th century that Knoxville, the stone's primary finishing and distribution center, became known as "The Marble City."