Tourism in Rome (with around 4 million tourists a year, making it the world's 39th most popular tourist destination). Other popular sites include St Peter's Basilica, the Forum Romanum, the Pantheon, the Trevi Fountain, the Spanish Steps, Via Condotti, Via Veneto, the Capitoline Museums, the Villa Borghese gardens, the Villa Giulia, Piazza Navona, the Basilica di Santa Maria Maggiore, the Basilica of St. John Lateran, the Piazza del Popolo, the Castel Sant'Angelo, the Campo de' Fiori, the Quirinal Palace, the Lateran Palace and the Palazzo Barberini, to name a few. Rome can be divided into several districts. The so-called historical center ("centro storico")
Fontana di Piazza Colonna to the foot of the column of Marcus Aurelius. The source of the water for the fountain of Piazza Colonna was only 67 feet above sea level; like the Trevi Fountain, the Fontana della Barcaccia, and the fountains of Piazza Navona, all connected to the Acqua Vergine, the fountain of Piazza Colonna was unable to jet water high into the air. The original project of Della Porta was to place an antique Roman statue of a sea god, called Marforio, in the fountain, against a background of a rocky grotto, behind which the column of Marcus Aurelius would be seen.