Last updated: October 2024

One thing you'll definitely notice when in Rome is the sheer number of churches. In fact, With nearly 1,000 churches,Rome is the city with the largest number of churches in the world! While they add to the city's charm, they also bring a challenge—keeping all their bells in sync. Imagine the inharmonious sound of hundreds of bells ringing at slightly different times! That's precisely the problem that Pope Pius IX ran into.

Today, it's easy to take for granted that the time on your phone matches the clock at the train station or the church clock. However, in the mid-19th century, keeping time synchronized across an entire city was still a real challenge. As a result, each church in Rome kept its own slightly varied time, causing their bells to ring at different moments.

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To solve this problem and to set a standard time for the ringing of church bells, Pope Pius IX introduced the Cannone del Mezzogiorno (meaning Cannon of Midday) in 1847. Each day at noon, a cannon fired from Castel Sant'Angelo, enabling everyone to set their clocks accurately.

But how did this work? The official sundial that marked noon sat in a small tower atop the Collegio Romano. A few minutes before noon, someone raised a sphere to the top of an antenna atop the nearby church of Sant'Ignazio di Loyola. The artillerymen at Castel Sant'Angelo could see the sphere, which signaled them to get ready. When the sundial hit noon, the sphere was dropped, and the cannon fired.

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The Cannone del Mezzogiorno continued even after Pope Pius IX's death. In 1903, the cannon moved to the slopes of Monte Mario and then to its current location at the Gianicolo in 1904. The tradition was only interrupted during World War II. Fortunately, 20 years later, the Cannone del Mezzogiorno was reinstated on the birthday of Rome (Natale di Roma) in 1959.

On quiet days, you can hear the cannon's shot from afar. Last September, I even heard it while strolling through Piazza Navona! If you have the chance, I highly recommend experiencing the Cannone del Mezzogiorno in person. It's entirelyfree and offers a great excuse to enjoy lunch in Trastevere afterward.