13 Best Sights in Rome, Italy

Although the line to peek through the keyhole of a nondescript green door in the Gran Priorato, the walled compound of the Knights of Malta, sometimes snakes around Piazza dei Cavalieri di Malta, the enchanting view is worth the wait. Far across the city, you'll see the dome of St. Peter's Basilica flawlessly framed by the keyhole and tidily trimmed hedges that lie just beyond the locked door. The priory and the square are the work of Giovanni Battista Piranesi, an 18th-century engraver who is more famous for etching Roman views than for orchestrating them, but he fancied himself a bit of an architect and did not disappoint.

Founded in the Holy Land during the Crusades, the Knights of Malta is the world's oldest and most exclusive order of chivalry. The knights amassed huge tracts of land in the Middle East and were based on the Mediterranean island of Malta from 1530 until 1798, when Napoléon expelled them. In 1834, they established themselves in Rome, where ministering to the sick became thelr raison d'être. Private, guided tours of the Gran Priorato are usually offered on Friday morning, but you must prebook by email.

This massive park, technically part of the Parco dell'Appia Antica, was named for the six remaining aqueducts that formed part of the famously elaborate system that carried water to ancient Rome. The park has some serious film cred: it was featured in the opening scene of La Dolce Vita and in a rather memorable scene depicting some avant-garde performance art in La Grande Bellezza. On weekends, it's a popular place for locals to picnic, exercise, and generally enjoy a day out with their kids or dogs.

One of Rome's oldest churches—built in the 6th century and restored in the late 19th century—is on the Piazza della Bocca della Verità, originally the location of the Forum Boarium, ancient Rome's cattle market and later the site of public executions. Although the church has a haunting interior and contains the flower-crowned skull of St. Valentine, who is celebrated every February 14th, it plays second fiddle to the renowned artifact installed out in its portico.

The Bocca della Verità (Mouth of Truth) is in reality nothing more than an ancient drain cover, unearthed during the Middle Ages. Legend has it, however, that the teeth will clamp down on a liar's hand if they dare to tell a fib while holding their fingers up to the fearsome mouth. Hordes of tourists line up to take the test every day (kids especially get a kick out of it).

The iconic Spanish Steps (often called simply la scalinata, or "the staircase," by Italians) and the Piazza di Spagna from which they ascend both get their names from the Spanish Embassy to the Vatican on the piazza—even though the staircase was built with French funds by an Italian in 1723. In honor of a diplomatic visit by the King of Spain, the hillside was transformed by architect Francesco de Sanctis with a spectacular piece of urban planning to link the church of Trinità dei Monti at the top with the Via Condotti below.

In an allusion to the church, the staircase is divided by three landings (beautifully lined with potted azaleas from mid-April to mid-May). Bookending the bottom of the steps are beloved holdovers from the 18th century, when the area was known as the "English Ghetto": to the right, the Keats-Shelley House and to the left, Babington's Tea Rooms—both beautifully redolent of the era of the Grand Tour.

For weary sightseers who find the 135 steps too daunting, there is an elevator at Vicolo del Bottino 8, next to the Metro entrance. (Those with mobility problems should be aware that there is still a small flight of stairs after, however, and that the elevator is sporadically closed for repair.) At the bottom of the steps, Bernini's splendid 17th-century Barcaccia Fountain still spouts drinking water from the ancient aqueduct known as the Aqua Vergine.

Alive with rushing waters commanded by an imperious sculpture of Oceanus, the Fontana di Trevi has been all about theatrical effects from the start; it is an aquatic marvel in a city filled with them. The fountain's unique drama is largely due to its location: its vast basin is squeezed into the tight confluence of three little streets (the tre vie, which may give the fountain its name), with cascades emerging as if from the wall of Palazzo Poli.

The dream of a fountain emerging full force from a palace was first envisioned by Bernini and Pietro da Cortona from Pope Urban VIII's plan to rebuild an older fountain, which had earlier marked the end point of the Acqua Vergine, an aqueduct created in 18 BC by Agrippa. Three popes later, under Pope Clement XIII, Nicola Salvi finally broke ground with his winning design. Unfortunately, Salvi did not live to see his masterpiece of sculpted seashells, roaring sea beasts, and diva-like mermaids completed; he caught a cold and died while working in the culverts of the aqueduct 11 years before the fountain was finished in 1762.

Everyone knows the famous legend that if you throw a coin into the Trevi Fountain you will ensure a return trip to the Eternal City, but not everyone knows how to do it the right way. You must toss a coin with your right hand over your left shoulder, with your back to the fountain. One coin means you'll return to Rome; two, you'll return and fall in love; three, you'll return, find love, and marry. The fountain grosses some €600,000 a year, with every cent going to the Italian Red Cross, which is why Fendi was willing to fully fund the Trevi's recent restoration.

Tucked away in a little nearby alley ( Vicolo del Puttarello 25), visitors can pay €8 for a tour that descends into a subterranean area that gives a glimpse at the water source that keeps the fountain running.

At the foot of the Spanish Steps, this curious, leaky boat fountain is fed by Rome's only surviving ancient aqueduct, the Acqua Vergine. The sinking ship design is a clever solution to low water pressure and was created by fountain genius Gian Lorenzo Bernini, together with his father, Pietro. The project was commissioned by Barberini Pope Urban VIII, and the bees and suns on the boat are symbols of the Barberini family. Looking for more symbolism, some insist that the Berninis intended the fountain to be a reminder that this part of town was often flooded by the Tiber; others claim that it represents the Ship of the Church; and still others think that it marks the presumed site of the emperor Domitian's water stadium in which sea battles were reenacted in the glory days of the Roman Empire.

The Gianicolo is famous for its peaceful and pastel panoramic views of the city, a noontime cannon shot, the Fontana dell'Acqua Paola (affectionately termed "the big fountain" by Romans), and a monument dedicated to Giuseppe and Anita Garibaldi (the guiding spirit behind the unification of Italy in the 19th century, and his long-suffering wife). The view from the terrace, with the foothills of the Appennini in the background, is especially breathtaking at dusk. It's also a great view for dome-spotting, from the Pantheon to the myriad city churches.

The Pantheon area is ice-cream heaven, with some of Rome's best gelaterias within a few steps of each other. But for many Romans, a scoop at Giolitti, which opened in 1900, is tradition. The scene at the counter often looks like the storming of the Bastille; remember to pay the cashier first, and hand the stub to the counter-person when you order your cone.

It's easy to overlook this tiny island in the Tiber, but you shouldn't. In terms of history and sheer loveliness, charming Isola Tiberina—shaped like a boat about to set sail—gets high marks. Cross onto the island via Ponte Fabricio, Rome's oldest remaining bridge, constructed in 62 BC. On the north side of the island crumbles the romantic ruin of the Ponte Rotto (Broken Bridge), which dates from 179 BC. Descend the steps to the lovely river embankment to see a Roman relief of the intertwined-snakes symbol of Aesculapius, the great god of healing.

In imperial times, Romans sheathed the entire island with marble to make it look like Aesculapius's ship, replete with a towering obelisk as a mast. Amazingly, a fragment of the ancient sculpted ship's prow still exists. You can marvel at it on the downstream end of the embankment. Today, medicine still reigns here. The island is home to the hospital of Fatebenefratelli (literally, "Do good, brothers"). Nearby is San Bartolomeo, built at the end of the 10th century by the Holy Roman Emperor Otto III and restored in the 18th century.

At the very heart of the Trastevere rione (district) lies this beautiful piazza, with its elegant raised fountain and sidewalk cafés. The centerpiece is the 12th-century church of Santa Maria in Trastevere, first consecrated in the 4th century. Across countless generations, this piazza has seen the comings and goings of residents and travelers, as well as intellectuals and artists, who today often lounge on the steps of the fountain or eat lunch at an outdoor table at Sabatini's. At night, the piazza is the center of Trastevere's action, with street festivals, musicians, and the occasional mime vying for attention from the many people taking the evening air.

The massive, 1st-century-AD arch was built as part of the original Aqua Claudia and then incorporated into the walls hurriedly erected in the late 3rd century as Rome's fortunes began to decline. The great arch of the aqueduct subsequently became a porta (city gate) and gives an idea of the grand scale of ancient Roman public works. On the Piazzale Labicano side, to the east, is the curious Baker's Tomb, erected in the 1st century BC by a prosperous baker (predating both the aqueduct and the city walls); it's shaped like an oven to signal the deceased's trade. The site is now in the middle of a public transport node and is close to Rome's first tram depot (going back to 1889).

The Terme di Caracalla are some of Rome's most massive—yet least visited—ruins. Begun in AD 206 by the emperor Septimius Severus and completed by his son, Caracalla, the 28-acre complex could accommodate 1,600 bathers at a time. Along with an Olympic-size swimming pool and baths, the complex also had two gyms, a library, and gardens. The impressive baths depended on slave labor, particularly the unseen stokers who toiled in subterranean rooms to keep the fires roaring in order to heat the water.

Rather than a simple dip in a tub, Romans turned "bathing" into one of the most lavish leisure activities imaginable. A bath began in the sudatoria, a series of small rooms resembling saunas, which then led to the caldarium, a circular room that was humid rather than simply hot. Here a strigil, or scraper, was used to get the dirt off the skin. Next stop: the warm(-ish) tepidarium, which helped start the cool-down process. Finally, it ended with a splash around the frigidarium, a chilly swimming pool.

Although some black-and-white mosaic fragments remain, most of the opulent mosaics, frescoes, and sculptures have found their way into Rome's museums. Nevertheless, the towering walls and sheer size of the ruins give one of the best glimpses into ancient Rome's ambitions. If you're here in summer, don't miss the chance to catch an open-air opera or ballet in the baths, put on by the Teatro dell'Opera di Roma.

This small, verdant park across the street from the Piazza del Quirinale is a good spot to stop and take a break. In the center sits an equestrian statue of King Carlo Alberto, the king of Piedmont-Sardinia during the turbulent period of the Reunification of Italy. There are benches to sit and kids often play on the grass. If you happen to be in the area at sunset, cross the street to see the spectacular sunset over Piazza del Quirinale and the rooftops of Rome.