On its face, this building is impressive simply because of its sheer size. Somehow it manages to look like it has much more glass cladding than buildings of a similar size. This is appropriate, because it is the headquarters for PPG Industries, formerly known as the Pittsburgh Plate Glass Company. Once known only as a smoky, soot-coated center of urban factories, the skies over Pittsburgh have since cleared and the water is somewhat clearer. The smokestack, steel, and coal industries have moved on leaving the city to reinvent itself as a center of technology and new, cleaner, industries. PPG is one of the city's oldest and largest companies, and this building provides a symbolic link between the old city, and the city Pittsburgh has become. Physically, the building was inspired by Victoria Tower, the lesser known of the two towers that frame the Houses of Parliament in Westminster (for a detailed description and photograph, click here). But at 635 feet, you would never know it from the ground where its glass façade blends in well with the new urban metropolis. It's only from one of the city's famous overlooks that you can see this building's true detail, a glass Gothic tower that pays homage the company and city's history while embracing the future.

• In 1999 PPG Place was sold for $185,586,420.00 to The Hillman Company. At the time of the sale, PPG said it never intended to own its namesake tower forever.

Photograph courtesy of David Gilliam