City Gates Overview - Baldur's Gate 2
The Athkatla City Gates is a very small map which you'll have to visit at some point during the game to leave Athkatla. Once you click on the edge of the map in this zone you'll enable fast travel to any World Map locations you have outside of the city. Also, on this map you'll also meet Flydian who will unlock Trademeet on your World Map. I'd recommend unlocking this city early since the vendors here are worth visiting.
After visiting this zone for the first time you should return 5 days later to witness a scene between Hanj and an unnamed merchant. If you defend the merchant and tell Hanj to leave him alone then the merchant will let you look at his stock before he permanently leaves the game. Check the wiki page for this merchant to see his stock, Contingency and Lower Resistance are 2 of the spells he carries that you can't get many other places this early in the game.
Last but not least, if you have Rasaad in your party and you pass through this zone you'll trigger an event for Rasaad's Companion Quest which will unlock the Abandoned Amphitheater location on the World Map.
Flydian: Speaking with this NPC and agreeing to help will begin the the Animal Trouble in Trademeet side quest and also unlock Trademeet on the World Map. This is a new town with vendors and quests that will lead you to 1 additional area on the World Map known as Druid Grove. I strongly recommend you do this chain of quests early on.
The Crooked Crane: The only notable thing inside of this inn is a Lich which you can find in a secret room in the back. If you need help beating this enemy I recommend you check out my BG2 Beginner's Guide for helpful tips and strategies. Once dead the Lich drops Wand of Cloudkill, Wand of Fire, Wand of Lightning, Rod of Terror and Sandthief's Ring. You can also find Daystar +2 in the chest behind him.