[citation needed] The estate contained over 30 monumental and scenic buildings arranged on a series of artificial esplanades at different heights and surrounded by gardens decorated with water basins and nymphaea (fountains).

In addition to the villa's impressive layout, many of the buildings are considered masterpieces of Roman architecture, making use of striking curved shapes enabled by innovative and extensive use of concrete.

The buildings were ingenious for the complex symmetry of their ground plans and are considered unrivalled until the arrival of Baroque architecture in the 17th century, initiated by Borromini, who used Hadrian's Villa for inspiration.

The villa was constructed near the ancient city of Tibur (modern-day Tivoli) by Hadrian as a retreat from the palace on the Palatine Hill in Rome which he is said to have disliked.

After Hadrian, the villa was used by his various successors (busts of Antoninus Pius (138–161), Marcus Aurelius (161–180), Lucius Verus (161–169), Septimius Severus and Caracalla have been found on the premises).

[6] During the decline of the Roman Empire in the 4th century, the villa gradually fell into disuse and was partially ruined as valuable statues and marble were taken away by Constantine the Great and his successors.

[8] In September 2013, a network of tunnels was investigated, buried deep beneath the villa; these were probably service routes for staff so that the idyllic nature of the landscape might remain undisturbed.

Although much major activity would have been engaged in during Hadrian's absence on tours of inspection of the provinces a great many people (and animals) must have been moving about the Tivoli site on a daily basis.

[10] The personal baths of Emperor Hadrian, begun around 118 AD included the innovative Heliocaminus room, which was heated by both sunlight and a hypocaust system.

It is on the upper terrace of the "Libraries" which is supported by a wall over 100 m long, adorned with alternating rectangular and curvilinear niches that probably contained statues and fountains.

This was one of the most sumptuous and grandiose parts of the villa, and the modern name reflects its very rich architectural and sculptural furnishings which were the reason for its being systematically plundered several times, starting from the 16th century, in ‘treasure hunts’.

[13] The main peristyle (61 x 51 m) enclosed a large garden with a central canal flanked by a symmetrical series of flowerbeds and pools, surrounded by a portico leading to rooms on the sides.

On the north side was the main entrance from the direction of the palace through the vestibule covered by an "umbrella" dome, a wonderful example of the Roman mastery of vaulted space and typical of Hadrianic architecture.

The south side of Piazza d'Oro has a series of curvilinear rooms centred on the monumental octagonal exedra covered by a cavernous dome.

The nymphaeum wall had seven alternate semicircular and rectangular niches, framed by columns and lined with precious marbles, and from which jets of water fell into a pool.

The play of water, with its sound and scenic effects, gushing from the monumental nymphaeum, running along the central pool and supplying the fountains in the garden, then disappearing underground before reaching the Vestibule would have been striking.

It was a huge garden on mighty artificial constructions to raise its edges forming a high platform, on which is a large rectangular pool of 232 x 97 m surrounded by four walls with colonnaded interior.

The Pecile platform and esplanade was made possible by the construction of an enormous substructure, the Cento Camerelle (100 rooms), to overcome the difference in height of up to 15 m with the valley below along the south and west sides.

However, brickstamps imply the construction of the Canopus was prior to 132, the year of the emperor's stay in Egypt and hence the building should rather be interpreted as an exotic representation of a Nile environment, only vaguely connected to the Canopic branch on the river delta.

The large exedra at the end of the pool features the imperial triclinium inside which is the stibadium (a semicircular masonry couch); banquets were held there, made spectacular by the water effects, the floating shows and the jets that surrounded the guests.

This room was used for meetings with the most important politicians and was covered in red marble that recalled the power of the emperor, as evidenced by the impressions of the slabs on the bedding mortar along the walls and the holes for the support clamps.

In 1736-1737 the statues of two Centaurs were found, the so-called "old" and the "young" by Aristeas and Papias, the Faun (or satyr) in red marble and the famous Mosaic of the Doves on the basin, currently in the collections of the Capitoline Museums in Rome.

Inside the complex, fragments of black marble statues were found, relating to Egyptian divinities or figures of priests which would confirm that this was the temple of the god Osiris-Antinous.

The villa was equipped with a vast system of underground passages, intended for the servants, who could thus move from one room to another or bring supplies without disturbing the emperor's leisure or the entertainment of his guests.

Many beautiful artifacts have been unearthed and restored at the villa, such as marble statues of Antinous, Hadrian's deified lover, accidentally drowned in Egypt, and mosaics from the theatre and baths.

A lifelike mosaic depicted a group of doves around a bowl, with one drinking, seems to be a copy of a work by Sosus of Pergamon as described by Pliny the Elder.

In 2011, the communal government of Tivoli announced plans, later cancelled, to build a waste dump in the vicinity of the villa and approved the construction of public housing on 120,000 sq.

While they commended the Italian government for its decision to abandon the construction of a waste dump in the Corcolle area, the committee requested the government "to inform the World Heritage Centre in due time about any major development project planned in the buffer zone of the property, including the housing development at Comprensorio di Ponte Lucano, for which a Heritage Impact Assessment should be included, in accordance with Paragraph 172 of the Operational Guidelines, before any irreversible commitment is made."

[citation needed] In 2019, UNESCO designated Hadrian's Villa as a site with special immunity from wartime activity due to its profound symbolic value.

[citation needed] In 2021 archaeologists led by researcher Rafael Hidalgo Prieto from the Pablo de Olavide University announced the discovery of remains of Hadrian's triclinium and a separate dining room that served as a model for the well-known Serapeum.