The Uchronians made this. According to SFGate: "Measuring almost 200 feet long, 100 feet wide and almost 50 feet tall, Uchronia is one of the most dominating structures on the playa this year. Born from a conversation in a Belgian pub, creators Jan Kriekels and Arne Quinze, along with 90 volunteers, built the timber installation over the past few weeks in Black Rock Desert."
It'll always be the Belgian Waffle to me. We love you, Uchronians!