Baptistry - interior
The circular baptistery was begun in 1152 and finished a century later by Nicola and Giovanni Pisano. Recently Italian musicologists cracked a five century-old acoustic code to reveal that Christianity's largest baptistery is a musical instrument, designed to mimic the pipes of a church organ. The acoustics beneath the 75-meter (250ft) cupola are so perfect that it must be either an incredible coincidence or the work of genius.
