Devon Dikeou's private Dikeou Collection gallery in a 16th Street high-rise is worth seeking out, but it's hard to find unless you know what you're looking for. Far more visible is its adjunct pop-up gallery in the Golden Triangle, which hosts openings and other special events, highlighting new additions to the collection in a more accessible spot. Think of this as a hands-on billboard for the collection itself, a spot in the heart of the museum district where the hustle and bustle brings an audience right to its door. Pop-up openings have introduced such works as Nils Folke Anderson's sculptural Styrofoam installation and, currently, the doctored photographs of Dutch artist Sebastiaan Bremer; during Denver Arts Week, the debut of Dikeou's extensive vinyl record collection provided some of the entertainment. The pop-up concept suggests an element of surprise — which means the impermanent Dikeou space is doing a surprising number of things right.