Brut. Journalist Jami Male attended Martin Garrix’s show at Red Rocks Amphitheatre on October 23, where he played his first ever B2B with Marshmello. The two surprised fans when they brought out Afrojack as a special guest before Garrix’s main performance. During their set, Marshmello and Garrix told the audience that they have known each other for 11 years, but have never played a B2B together until now. Garrix also said that playing at Red Rocks was a bucket list item for him. Located in Morrison, Colorado, Red Rocks Amphitheatre is recognized as one of the most unique venues in the United States, with a geological formation that has not been replicated anywhere in the world. The amphitheatre is located between two 300 ft monoliths, providing a stunning environment and enhanced acoustics for any performance at the venue.