If you looking for an after hours lounge to relax in, Gin Palace is a swanky, quieter, dim-lit place with comfy sofas and high-style cocktails. Undergrounds aren't usually classy, but this one exceeds that and all typical speakeasy expectations. We went on an off night and arrived a little on the early side coming from a jazz club*. Fresh cocktails are chilled on ice and the recipes are deliciously creative, while fresh lilies and Boston leather armchairs evoke quite a mysterious old-world vibe.
Aside from the impressive cocktails and atmosphere, best part about visiting this lounge as a tourist and epicure was we spontaneously had a drink expert give us a personal absinthe tasting and historical background to the drink. We had absinthe before, but never learned about it or tasted it the way one would wine at a winery. It was quite intense, and we were so grateful for the server to share his expertise. Very happy it wasn't crowded, and I'm not sure if they were bored because it was early, but we were extremely pleased that the staff was so friendly. The feeling definitely made us think we were in another century and country. I would definitely recommend visiting it's quite a unique experience in more than one way.
*Side note, I had no idea how good live music or the jazz scene in Melbourne was, and "early side" is probably 11:00 pm or 23:00)