Nero had his Domus Aurea constructed after the fire of AD 64 (which it's rumoured he had started to clear the area). Named after the gold that lined its facade and interiors, it was a huge complex covering up to a third of the city. The excavated part of the site has been repeatedly closed due to flooding, but opened for weekend guided tours from late 2014; check the website for current opening status.
The palace was full of architectural invention, a more splendid palace than had ever been seen before. However, Nero’s successors attempted to raze all trace of his megalomania. Vespasian drained Nero’s ornamental lake and, in a symbolic gesture, built the Colosseum in its place. Domitian built a palace on the Palatino, while Trajan sacked and destroyed the 1st floor and then entombed the lower level in earth and used it for the foundations of his public baths complex, which was abandoned by the 6th century. This burial of the palace preserved it; the section that has been excavated lies beneath Oppian Hill. Wear warm clothes to visit as the palace now lies underground and is damp. Remarkably, the humidity has helped preserve the frescoes in the chambers, though this may only be seen in one small cleaned area – the rest have not been restored. Tours last an hour and 15 minutes and are guided by archaeologists who are extremely knowledgable about the site.
During the Renaissance, artists (including Raphael and Pinturecchio) lowered themselves into the ruins, climbing across the top of Trajan's rubble in order to study the frescoed grottoes, and Raphael reproduced some of their motifs in his work on the Vatican.
