A modest-looking office building on Water Street that occupies an outsized place in architectural history: completed in 1864 to a design by Peter Ellis, it is widely credited as the world's first building with a metal frame supporting a "curtain wall" of glass — a structural concept that would later define skyscraper architecture in Chicago and New York.
Contemporaries hated it: one critic in The Builder called it "a great abortion." But the principle was sound, and influenced John Wellborn Root, who later designed buildings in Chicago. The five-storey building is still in use as offices and can be admired from the street. Ellis's other Liverpool building, 16 Cook Street, is also worth a look.