John T.
Yelp
A surprisingly decent bar in the heart of the CBD within a couple of steps to Flinders station. A huge selection of beers for a Melbourne bar and at least one on cask (hand pump). I was there on a Saturday night and people were streaming in from a game or something so it was pretty crowded.
Exemplifies many of the best qualities of Melbourne's good bars (a small group as far as I can tell). Many of the bar (or hotels) seem pretty specialized in terms of ambiance or clientele. For a city this size there are surprisingly few bars in general and even less that fit my American sensibilities. I am basically looking for a place with an actual bar that one can sit at (not just a long serving station), a good number of beers, preferably relatively dark, and a good mix of people. A place to sidle up to the bar, get a beer and maybe end up in an unplanned conversation with the bartender or another patron. A lot of the the bars around are either fancy cocktail bars or hotels that seem to actually be like hotel bars in Europe, antiseptic with little atmosphere, a little too fancy, and either catering to people attempting to impress dates or footy watching. Now, there is nothing wrong with this in principle, but I am sometimes just looking for a bar to get a beer and hangout. Young and Jackson's fits the bill.
It is not exactly a "dive bar" in the American sense, it is fancy and overly lit. But, at least when I was there, it seemed to be populated by an interesting diversity of people that led to some good conversation and people watching. The bartenders were nice and very helpful, suggesting different beers and seeming genuinely friendly.
The prices are pretty good by Melbourne standards and, as others have noted, its location makes it a perfect stop before getting on a train home. The place also has a lot of history as some of the other reviewers have noted. Overall, very solid choice in the CBD.