So you think a marathon’s tough. Try running 6 marathons, one after the other, until your feet bleed and your lungs wither like kalamata olives in the hot Greek sun.

That’s what racers at this year’s Spartathlon have done, tracing a 153-mile route from Athens to Sparta. It is a route that ultra runners race every year, following in the footsteps of the legendary messenger Pheidippides, who 2,500 years ago, ran from Athens to Sparta seeking reinforcements on the battlefield to take on the invading Persians.

Brave distance runners have been recreating his journey ever since, with 2012 winner Stefan Stu Thoms crossing the finish line September 29 with a time of 26 hours 28 minutes. Racers haven’t always been so fast. Many drop out before they see the finish line.

The Legend

In 490 BC, 600 Persian ships set sail for Greece intending to add the fertile Mediterranean peninsula and its people to a growing Persian Empire. The Athenians caught wind of the impending invasion. They knew they needed backup. And so they dispatched a fleet-footed soldier named Pheidippides over the horizon to Sparta, 153 (240 km) away. According to legend, the journey took less than two days, a shockingly quick time for such distance covered over hot and rugged terrain. Days later, an alliance of city-states beat the Persians at Marathon. Days later, Pheidippides ran from Marathon to Athens, a 25-mile journey that inspired the modern marathon, and then collapsed and died while announcing the Greek victory. With his death, a Greek passion for endurance running was born — a tradition that has reached its pinnacle in the 153-mile Spartathlon.

The Race

The Spartathlon is one of dozens of races held across the globe every year known as ultramarathons, each longer than 26.2188 miles. At 153 miles, the Spartathlon is longer than most ultramarathons, with only a handful of racers ever finishing the route in 24 hours. To do so, a Spartathlete must run an average mile of 9 minutes 24 seconds. That’s about two-times slower than elite marathoners run during a 26-mile race. Spartathletes are “slow” because 153 miles is an unbelievably difficult distance. Also, the terrain is inhospitable.

See the course map here.

Starting in the shadow of the Acropolis at 7 am and cutting across Athens’ sun-baked asphalt, runners jog west in mid-90s temperatures, plodding along the rolling hills of the southern coast en route towards Corinth. There, the route turns south into Greece’s southern peninsula, the Peloponnese. That’s when the skies go dark and the exhausted racers must push uphill, with the daunting Sangas Pass standing tall in the way of Nestani, the 106-mile checkpoint that racers must cross in 24 hours 30 minutes or else be pulled off the course. This year, only 72 of 310 competitors crossed the finish line, with many runners dropping out before Nestani.

And from Nestani the race doesn’t get any easier. The highest point in the race, 4,000-foot Mount Parthenio, looms ahead in the darkness of night, with little more than a trail of glowsticks leading runners to its summit and over into dawn. At sunrise, the fastest racers will run into the misty Evrotas Valley, pushing across a paved road flanked by farmland frosted in dew, soon burnt away by the new sun that bakes runners as they push onward.

At the village of Voutiani, all that remains is a 10k. With 236 kilometers already crushed beneath the soles of the remaining racers’ feet, the road ahead will be one of the toughest 10ks Spartathletes ever run. At this point, it’s too late to turn back. A statue of King Leonidas, standing proud in the center of Sparta, beckons runners forth. 245.3 kilometers after they left Athens, the strongest runners finally arrive at the finish line, having completed one of the most difficult races on earth.

The Racers

On September 29, 46-year-old German ultrarunner Stefan Stu Thoms won the Spartathlon in 26 hours 28 minutes, beating out second place Japanese runner Tutsuo Kiso by 8 minutes. 36-year-old Elizabeth Hawker was third across the finish line, completing the race in 27 hours 2 minutes, a women’s Spartathlon record. The top 3 finishers were among only 72 runners to finish, with 238 runners or 77% of all competitors dropping out.

Stefan Stu Thoms’ time was well off the Spartathlon record of 20 hours 25 minutes, set in 1984 by Greek running legend Yiannis Kouros. At that race, Kouros ran 8-minute miles, a blistering pace for such distance. Kouros also won the inaugural race in 1983, in addition to the 1986 and 1990 Sparathlons. His 4 champion times, all under 22 hours, are the fastest 4 times in Spartathlon history.

More recently, American ultramarathon star Scott Jurek has owned the Spartathlon. The famous vegan won 3 straight titles from 2006-2008, with Jurek’s 2008 time of 22 hours 20 minutes the fifth fastest time ever clocked at the Spartathlon.

It’s unclear if anyone will ever come close to matching the times set by Yiannis Kouros, who has been called “Pheidippides Successor.” In 2005, Kouros took the Spartathlon to a historically insane new level, recreating Pheidippides’ round trip from Athens to Sparta and back to Athens. Kouros completed the 306-mile journey on sports drink, running refreshments and zero sleep in 53 hours and 43 minutes. Nobody has come close to matching the legend of Pheidippides ever since.