What? Don't listen to this post, Enworld. Decline and Fall of the Roman Empire is a beautiful book. The historiography is outdated, but the prose is wonderful. It's a delight to read.
Added by edit: In fact, now that I think about it, I reread it after I visited Rome. I remember standing on the Capitoline Hill looking at the ruins of the old forum and being reminded of Gibbon's description of Poggius surveying the ruin of Rome from the same spot and contemplating the city's fall some 600 years previously. Gibbon talks then about the beginnings of the transformation of the ancient ruins into a tourist attraction for foreigners (this was in the 18th century):
"The map, the description, the monuments of ancient Rome, have been elucidated by the diligence of the antiquarian and the student: and the footsteps of heroes, the relics, not of superstition, but of empire, are devoutly visited by a new race of pilgrims from the remote, and once savage countries of the North."