The Sphere in Las Vegas got an unexpected visitor Wednesday ... an activist-climber scaled the towering 367-foot-tall structure.
Video of the individual walking around the top of The Strip's newest concert venue started to crop up online shortly after he began ... and the climber -- Maison Des Champs -- also posted to Instagram confirming he was the one who'd made the daring climb.
On Top Of The Sphere Instagram / @prolifespiderman
Maison explained in the short clip that he was doing the climb to raise money for a homeless woman and her unborn child .