Meagan American Ninja Warrior
Meagan Martin tried to make history Monday night during the Denver finals of "American Ninja Warrior." NBC

"American Ninja Warrior" returned to Denver Monday night for the last city finals, sending the final 15 contestants on to Las Vegas. The Las Vegas finals begin next Monday at 9 p.m. EDT, with the NBC show's Season 6 finale set for Sept. 15.

After Kacy Catanzaro became the first woman to qualify for the Las Vegas finals at the Dallas city finals (three women finished regional qualifying courses for the first time this season), all eyes were on Meagan Martin to see if she would be next. But even with Catanzaro cheering her on from the sidelines, Martin could not make it, going out on the “spikes into cargo net.”

Denver still made history, though, as Jon Stewart, 52, became the oldest competitor to complete a city finals course on “American Ninja Warrior.” Stewart finished with a time of 8:58:50 to punch his ticket to Vegas.

Isaac Caldiero finished the course with the fastest time, clocking in at a whirlwind 5:48:41. Caldiero and Stewart were two of only six competitors who completed, the others being Paul Kasemir, Brian Arnold, Ian Dory and Dr. Noah Kaufman. Fans may remember Arnold from last season's Las Vegas finals, where he went further than any American ever on stage 3.

Rounding out the 15 who will advance to Las Vegas were the nine competitors who went far enough in the course the fastest: Daniel Larson-Fine, Justin Kydd, Karson Voiles, Yen Chen, Dan Entmacher, Robin Pietschmann, Matthew Wilder, Joel Brady and Lance Pekus. All fifteen will join the finalists from the four other cities (Dallas, Venice Beach, St. Louis and Miami) in Las Vegas.

Tune in for the start of the Season 6 Las Vegas finals on Monday, Aug. 11, at 9 p.m. EDT on NBC.

Who are you rooting for in Las Vegas? Tweet your thoughts to @Ja9GarofaloTV.