Obelisk of Montecitorio

A 6th-century BC red granite obelisk of Pharaoh Psamtik II, brought to Rome by Augustus in 10 BC to serve as the gnomon of the largest sundial ever built — the Solarium Augusti, with a bronze meridian line stretching across roughly 100 metres of pavement. Sections of the original meridian line are still preserved in basements beneath nearby buildings, and a modern bronze line has been laid into the cobblestones around the obelisk's base to indicate where the ancient one ran.