Pisa's 54-metre-high Baptistry is Christianity's largest, and a fine example of the transition between the Romanesque and Gothic architectural periods. Acoustically perfect, the Baptistry is called a "giant musical instrument", as its resonance mimics that of an organ.
Like Pisa's most famous building, the Leaning Tower, the Baptistry also leans 0.6° due to being built on the unstable sand of the area.