After the Great Fire of Rome (64 AD), Nero seized 120 hectares of destroyed city center and built the DOMUS AUREA — the Golden House. 300 rooms. Walls covered in gold leaf, mother of pearl, and precious stones. Ceilings that rotated and rained perfume. An artificial lake where the Colosseum now stands. A 35m bronze statue of Nero as the Sun God (the Colossus — which gave the Colosseum its name). When Nero died (68 AD), successive emperors BURIED IT. Vespasian drained the lake and built the Colosseum on top. Trajan built his baths directly over the Domus. For 1,400 years, the palace was underground, forgotten. In the 1480s, a Roman fell through a hole into a painted cave. Artists — including Raphael and Michelangelo — lowered themselves down by rope to see the frescoes. They called the style "grotesque" (from grotta/cave) — the word we still use comes from THESE ROOMS.
The visit is UNDERGROUND. Hard hats required (provided). The rooms are excavated beneath Trajan's Baths on the Oppian Hill. The Octagonal Room: The engineering marvel — a concrete dome with an OCULUS (like the Pantheon, but 50 years EARLIER) that may have been the rotating dining room described by Suetonius. The frescoes: Painted scenes of mythological creatures, garlands, architectural fantasies — the GROTTESCHE that Raphael copied for the Vatican Loggia. The VR experience: At several points, you put on VR headsets and see the rooms RECONSTRUCTED — gold ceilings, marble floors, the frescoes in their original colors. The contrast between the dark, stripped underground and the VR's golden magnificence is devastating.
Via della Domus Aurea 1 (Colle Oppio park, near the Colosseum). €16 + €2 booking fee. MANDATORY guided tour (1h15, Italian or English, Sat-Sun only + some Fridays). Book at coopculture.it — sells out weeks ahead. Maximum 25 people per tour. Bring a light jacket (underground is 10-12°C year-round, even in Roman summer). Metro B: Colosseo (5 min walk). Combine with: The Colosseum is directly below — Nero's lake became Vespasian's arena. The connection is PHYSICAL. Rome →