It's the world's longest certified road race and it's not through some beautiful landscape - the course is just a half-mile, or a roughly 800 metre block in the New York borough of Queens.
To finish on time, Harita Davies and the nine other runners taking part in the Sri Chinmoy Self-Transcendence race have to do an average of 110 laps - or approximately 100 kilometres - a day. It's the second time Harita's taken on the challenge - and this year she's the only woman taking part. Indira spoke to her as she pounded the pavements on her way around the course yesterday.