Nero's "Golden House" gives a good sense of the excesses of Imperial Rome. After fire destroyed much of the city in AD 64, Nero took advantage of the resulting open space to construct a lavish palace so large that it spread over four of Rome's seven hills. A circular opening in the roof of the banquet hall created the illusion that the room itself was revolving. Today the palace remains impressive in scale, although it requires a bit of imagination to envision its former grandeur (a mediocre audio guide is some help). One wing caved in in early 2000 and remains closed at least through 2005. The underground site is cold even in summer, so take something warm to wear. Reservations are highly recommended. COST: EUR5 plus EUR1.50 reservation fee; EUR10 with tour; audio guide EUR2.