Santa Maria degli Angeli e dei Martiri, Rome
FOR LOVERS OF SCIENCE and history the ruins of the Baths of Diocletian are the gift of Imperial Rome that keeps on giving.
Completed about 306CE, the complex, near Rome’s Termini railway station, has in later times been adapted for a variety of uses. It includes the Church of San Bernardo alle Terme, parts of the National Roman Museum and the fascinating Basilica of Santa Maria degli Angeli e dei Martiri (St Mary of the Angels and the Martyrs).
The basilica’s design was one of Michelangelo’s last works; its construction began before his death in 1564 and extended to the 18th century. Its soaring nave is adapted from what was once the frigidarium (cold room) of the baths; its entrance is set into a remaining, crumbling semi-circular wall facing the Piazza della Repubblica.
Inside is the basilica’s primary scientific treasure: the meridian line designed and built in 1700–02 by polymath Francesco Bianchini, assisted by a mathematician named Gianfranco Maraldi – the nephew of astronomer Giovanni Domenico Cassini, who created a similar meridian line in 1655 in the Basilica San Petronio, Bologna.
Pope Clement XI wanted Bianchini’s device to check the accuracy of the Gregorian calendar, to use as a tool for predicting Easter, and especially so Rome had a meridian line as splendid as Bologna’s.
The ornate bronze line, set in yellowwhite marble, angles across 45 metres of the basilica’s floor. It’s beautifully decorated with technical markings, special calendar dates and signs of the zodiac. Sunlight reaches it through an improbably small aperture (about 2–4 centimetres) set 20.3 metres above the floor in the arch of the Albergati Chapel, on the south side of the basilica’s transept.
Bianchini’s meridian line is widely considered the best of several similar devices in European churches. In January 1713 he became a Fellow of the Royal Society of London; he was proposed by Sir Isaac Newton. Bianchini died in 1729.