After the great fire in 64 AD, Emperor Nero built a great palace complex called Domus Aurea on the Oppian Hill. However, it was a symbol of decadence for the successers of Nero. So, the complex was stripped of its marble, jewels, and ivory in short time, and it was destroyed during the rule of Trajan in 104.
Here is an animation showing what Domus Aurea looked like in the past, and what it looks like today.
Soon after Nero’s death, the palace was filled with earth and built over except for the Oppian villa which continued to be inhabited for a while. These later buildings include the Baths of Titus, Flavian Amphitheatre (the Colosseum), and Temple of Venus and Roma. These buildings covered the palace in 40 years, which actually ensured the protection of wall paintings from moisture.
The palace was accidentally rediscovered in the 15th century when a young Roman fell into a cave filled with paintings. Later, several Renaissance artists including Raphael and Michelangelo crawled into the cave to study these paintings. Unfortunately, the discovery of the ruins also led to their exposure to humidity which led to the collapse of a chunk of ceiling in the 20th century. The trees above the ruin also cause further damage with their roots. Moreover, architects think that Domus Aurea will eventually collapse due to the weight of earth. So, the structure was closed in 2005 for further restoration works conducted until 2021 when it was reopened.
