The campanile, or freestanding bell tower, of the Duomo Pisa was built in the 12th century by Bonnano Pisano.

Although a masterpiece of architecture, it is mostly famous for its tilt. It rests on highly unstable sandy soil which gives the famous Torre de Pisa its tilt – and its nickname. In fact, you might notice that the baptistry leans the other way.

A square in Rome that hosts four Republican Roman temples, and the remains of Pompey's Theater. It is located in the ancient Campus Martius.

The La Scala Opera House is the premier opera venue of the world.

It was inaugurated in 1778 and is still in operation, having hosted many opera legends, including Arturo Toscanini, Maria Callas and Luciano Pavarotti. The La Scala Museum – Museo Teatrale alla Scala –  is adjacent to the foyer and contains an extraordinary collection of art, costumes, and other memorabilia of opera and La Scala's history.

The House of the Vettii is on a back street opposite a bar.

Named for its owners, two successful freedmen – Aulus Vettius Conviva and Aulus Vettius Restitutus – it was a luxurious residence. It has many well-preserved murals, including a number of erotic works – though most of these are often kept behind locked doors.

In the entrance foyer is a large image of Priapus with a bag of coins and a set of scales. The enclosed formal garden still allows a glimpse of the wealth and taste of its owners.

Named for a small bronze statue of a dancing faun found on the site, this residence is best known for the Have  – Welcome – mosaic at the entrance, and the Alexander Mosaic, one of the most celebrated mosaics to have survived.

Once among the largest, most luxurious private residences in Pompeii, the House of the Faun occupies an entire city block.

See also: The Ruined City of Pompeii

A gracious villa on the Via Dell'Abbondanza – street of abundance – in Pompeii, and fronted by great bronze doors, the House of Loreius Tiburtinus is also sometimes called the House of Octavius Quartio.

This house stands out for its extensive gardens and excellent, well preserved artwork.  Conveniently located – the street that was closed to cart traffic in ancient times – and boasting well decorated rooms, many guests must have passed through.

The gardens have fountains at their centers, with many frescoes and statuettes around.

Shaped much like a giant question mark or inverted S across the middle of the city, the Grand Canal is Venice's largest and most famous thoroughfare.

It’s traveled by water buses, private water taxis called vaporetti, and, as many tourists already know, gondolas. Traveling the canals is the best way to see Venice's beautiful waterfront architecture, places and museums.

Most traffic travels the length of the canal. In addition to the canals, the city is connected by about 400 footbridges. The largest, Ponte Rialto, is covered and houses a number of small shops.

These Public Gardens cover 160,000 square meters, and has a small lake with geese and fish, faux rock hill, rides, a miniature train and refreshment stands.

The shopping Galleria is not only known for its fabulous shopping but also for its huge stained glass domed roof (48m), truly magnificent in its array of colors. It is named after Vittorio Emanuele II, the first ruler of Italy.

The Colosseum – or Coliseum – is probably the most iconic symbol of Imperial Rome, as well as one of the great works of Roman architecture and engineering. The first permanent amphitheater to be built in Rome, this enormous amphitheater was inaugurated by Titus in the 1st century.

Although it is now near ruins, the Colosseum was used for almost 500 years for gladiatorial contests and public spectacles, including mock sea battles, executions, reenactments of famous battles, and Classical dramas.