I know how to get into Crystals from the Aria/ W-A side, but is there an entrance if you were walking south from Cosmo? Is it on street level or up on that overpass?
Yes, there is an entrance to Crystals from the south side, if you're coming from the Cosmopolitan. The entrance is located at street level, but it's a little tricky to spot depending on your location on the sidewalk.
To sum it up: If you're walking south from Cosmo, the easiest and most direct entrance to Crystals is the street-level entry located near the intersection of Harmon and Las Vegas Blvd. It’s right in front of the pedestrian overpass, so you won’t miss it. If you prefer the elevated experience, you can use the overpass to enter Crystals at the second level, but street-level will be quicker and more straightforward.