Athens Authentic Marathon in Athens
The only marathon run on its original 1896 course, from the town of Marathon to Athens's Panathenaic Stadium, honoring the race won by Spyridon Louis at the first modern Olympics and, further back, the legend of Pheidippides's run to announce victory over the Persians in 490 BC.
Every other marathon in the world takes its name and distance from an event that first happened on this exact stretch of road.