Marcia Mueller wants to build a gateway to her neighborhood and downtown Denver. “My intent has always been to knit this intersection together,” Mueller said. Her plan is to build a 300-square-foot “jewel box” retail building on the corner of Umatilla and 29th Avenue in LoHi, where four streets meet in one of Denver’s more complex intersections. “That’s going to be like an amazing little glass box,” Mueller said.