Been thru BG once but can't remember how to enter the city. The draw bridge isn't down. A little assistance would be great.

IIRC if you've been through the Cloakwood Mines the drawbridge should be down. Did you maybe miss an important dialog in the Mines?

You Have To Be In Chapter 5 IIRC

WENT BACK INTO THE MINES BUT DON'T THINK I DID ANYTHING DIFFERENT. THE SLAVES WERE ALREDY OUT, BUT I DID OFF SOME MAGE WHO WAS TORTURING SOME MINERS. MAYBE THAT WAS IT. GLAD I DID GO BACK THOUGH. I FOUND A KNOCK SPELL AND, SINCE IMMOEN COULDN'T OPEN MANY OF THE LOCKED CHESTS, I USED IT TO GET A FEW FINE ITEMS.

THANKS FOR THE TIP

Yep, that was it. That Mage you're talking about is Davaeorn, and killing him causes the game to advance to Chapter 5. Which in effect enables you to enter the city.