Possible Clues:

• The longest foot race in sport
• Brought about no harm at gruelling event
• It's roughly 95-Across kilometers
• Scene of Greek victory over Persians in 490BC
• Damage new hat on long-distance race
• Race devised for the first modern Olympics in 1896
• Revolutionary hospital on site of battle long ago
• Mum ace in horrendous North Run
• Old woman advanced in explosive North Run
• Race run by Kipchoge in under two hours