Is the feature located in an area with corrals, buildings for exhibition, barns, outdoor track, the kinds of things one would expect at a county fairgrounds? If this is the features called "National Western Stockshow complex, I would call it the fair/exhibition/rodeo feature code.
Is the feature on the covered stadium on the south side of I-70? Then I would probably call it a stadium. Lots of things go on in this building besides the NW Stock Show.