A Prague must! This IS a Czech pub. Go here. Loud, drinkers, dark wooden benches and pilsner fresh from the tank.
If you want to drink pure gold, the Tank Budvar here would be it. This pub has been around for a long time (1466).
Come in the Golden Tiger and take a drink from the coolest mugs in Prague.
A hole in the wall pub directly under the castle, the Hippo (Hrocha) has a cast of regulars.
The Black Bull feels like its been around since before the castle. One of the few places that serve Velkopopovický Kozel.
U Houbaře (the mushroom picker) is not in the center, but well worth an easy tram ride.