How far would you go to get into the Guinness Book of World Records? One intrepid New Yorker has completed an amazing feat that many would think impossible: he hit every station in the 660-mile NYC Subway system in under 24 hours. For two years in a row, Matthew Ahn has hopped on a subway car, visited every stop in the entire system, and hopped off at the final station in less than a day’s time. His latest record was verified last week by Guinness officials.

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Matthew Ahn is the 25-year-old lawyer who took on the so-called “Subway Challenge” to beat his own world record. Ahn successfully hit each of NYC’s 468 subway stations in 21 hours and 49 minutes in Jan. 2015. Sadly, his record was nullified when the 34th St-Hudson Yards station opened last fall. To defend his title, Ahn decided to give it another go in July of this year. With The New York Times tagging along to document the authenticity of his record-breaking commute, Ahn spent part of a recent weekend riding the subway rails to beat his previous time, even with the additional station to visit.

Related: This is the first MTA subway station ever to be awarded LEED Certification

Ahn keeps his specific route top secret, but his world record accomplishment started and ended in Queens. He began at the Far Rockaway–Mott Ave station at 2:02 a.m., a time he chose since the subway is a virtual ghost town. His trip lasted 21 hours, 28 minutes and 14 seconds, finishing at Flushing–Main St station. Ahn recommends that anyone who wishes to challenge his title think long and hard about taking on the Subway Challenge. His top advice for plotting a record-breaking route: start late at night, maximize the frequency of trains during rush hour, and avoid Manhattan during rush hour.

That last one seems like a no-brainer.

Via Curbed

Images via Guinness World Records and MTA