From the World Heritage inscription:
In its urban structure and its architecture, Verona is an outstanding example of a town that has developed progressively and uninterruptedly over 2,000 years, incorporating artistic elements of the highest quality from each succeeding period. It also represents in an exceptional way the concept of the fortified town at several seminal stages of European history.
The city is situated in northern Italy at the foot of Monte Lessini on the River Adige. It was founded by ancient tribes and became a Roman colony in the 1st century BC, rising rapidly in importance. It was occupied by the Ostrogoth Theodoric I (5th century), by the Lombards, and by Charlemagne (774). In the early 12th century, it became an independent commune, suffering during the wars of Guelphs and Ghibellines. It prospered under the rule of the Scaliger family and particularly under Cangrande I. It fell to Venice in 1405, was part of the Austrian Empire from 1797, and joined the Kingdom of Italy in 1866.
The core of the city consists of the Roman town in the loop of the river. The Scaligers rebuilt the walls, embracing a much larger territory in the west and another vast area on the east bank of the river. This remained the size of the city until the 20th century. The heart of Verona is the ensemble consisting of the Piazza delle Erbe (with its picturesque vegetable market) and the Piazza dei Signori, with their historic buildings, including the Palazzo del Comune, Palazzo del Governo, Loggia del Consiglio, Arche Scaligere and Domus Nova. The Piazza Bra has a number of classicist buildings.
In the north of Italy, Verona is one of the richest cities in Roman remains. These include the Porta Borsari, a city gate at the beginning of the decumanus maximus; the Porta Leoni, only half of which remains, attached to a later building; the Arco dei Gavi, dismantled in the Napoleonic period and rebuilt next to Castelvecchio in the 1930s; the Ponte Pietra; the Roman theatre, excavated in the mid-19th century and restored for use in spectacles; and the Amphitheatre Arena, the second-largest after the Colosseum in Rome (originally a wall of three orders surrounded it, but this collapsed in an earthquake in the 12th century).
Despite all the history which can be found in Verona, it is still best know for someone who never once visited: William Shakespeare.
The story of Romeo and Juliette still is a huge draw for the city. The House of Juliette is a tourist attraction run by the city and there is a bronze statue of Juliette in the courtyard of the house underneath a balcony.
The attractions related to a fictional story by a 16th Century English playwright are not what make Verona a world heritage site, however. Verona dates back to the Romans and their presence is felt by the largest and most significant attraction in the city: the Roman Arena.
The Verona Roman Arena is one of the best preserved Roman amphitheaters in the world. It still is used to host performances.
Verona also has a host of fortifications which ring the city which harken back to its days as a city state.
Verona is best seen as an attraction in itself but can be visited on a day trip from Venice, which is only 1 hour away by train.