World Overview for Baldur's Gate Zones
On this page you will find succinct information about what is in each section of Baldur's Gate (the town, not the game). Essentially what I have done is gone through everything in each zone and I singled out the most important quests, items or events to complete and wrote them down.
Very unique items, best in slot items, available companions, Steam Achievements and things of that nature are what made my lists below. Those of you who would like to see a different version of this same information with a bit more details check out my Baldur's Gate Walkthrough - Chapter 5.
AR0100 (Baldur's Gate Northwest): Degrodel's House is worth visiting as it leads to the Searching for Balduran's Helmet Quest which is a BiS Helm and Cloak. The Helm and Cloak Inn has an event which will reward you with the Battle Axe of Mauletar which is another BiS item. For a quick and easy EXP quest I recommend Quinn's Friend as well. Last but not least you can also find Skie Silvershield and recruit her as a companion in Entar Silvershield's Estate.
AR0200 (Baldur's Gate North): Aside from the Ducal Palace which is part of the main story, the best optional content in this section is... Ramazith's Tower which acts as a mini dungeon with multiple floors of enemies and a couple of good items to get. Jardak's Home is also found here which is where you can obtain the Helm of Glory a BiS helm.
AR0300 (Baldur's Gate Northeast): The Marek and Lothander quest has its first flag event in the southern part of this district. Blushing Mermaid is worth visiting since you'll find Larze on the first floor who drops Gauntlets of Weapon Skill, a BiS glove item. The Splurging Sturgeon is another location you can visit
AR0600 (Baldur's Gate West): The Hall of Wonders is found here which is where you can meet Alora (night only), a potential companion. You'll also find Ragefast's House in this district which is part of the The Captive Nymph Side Quest. Tremain's Son is another side quest worth doing in this section of town, I talk about both of these quests in Chapter 5 of my walkthrough. Also, both of these quests give achievements in the Steam version of the game.
AR0700 (Baldur's Gate Central): Felonius Gist's Manor can be found in this district, you'll find 5 stone statues here that you can free using Stone to Flesh Scrolls. This is all part of the Helm of Balduran and Cloak of Balduran Side Quest. Loathander is also found here who is involved in an extremely annoying side quest by the name of Marek and Lothander. If you don't finish the side quest within 10 days once it begins you'll get a Game Over.
AR0800 (Baldur's Gate East): When you first arrive in Baldur's Gate this is the section you will enter. You'll find Sorcerous Sundries here which is the best magic & spell shop in town; the 2nd floor has a fight/event and the 1st has the shop along with the Arkion and Nemphre Side Quest. The Thieves' Guild is in this section of town too and contains a Manual of Quickness of Action (+1 Dex) along with a couple of side quests that IMO are not worth doing. Elfsong Tavern is the last notable place, Brevlik will give you the Larceny at Hall of Wonders Side Quest and Cyrdemac for A Contract Killing Side Quest.
AR0900 (Wyrm's Crossing): A potential companion is here named Quayle (Cleric/Illusionist) and there are 2 quests to complete here, Quinn's Friend and The Fishermen and the Priestess. The Fishermen and the Priestess is an Achievement on Steam. Your first time through this zone during Chapter 5 you'll also run into Scar, a Flaming Fist soldier who asks you to investigate the Seven Suns.
AR1100 (Baldur's Gate Southwest): You'll visit this section of town often for Story Quest objectives. The Flaming Fist Headquarters is the main building in this part of town that you'll often visit for both Scar and Duke Eltan. Scar will give you a Side Quest early on to investigate the Seven Suns building too which is filled with Dopplegangers. The Merchants' League Estate is another large building in this part of town but you can only access it if you left Aldeth alive in the Cloakwood Forest. Aldeth will give you Investigating the Merchant League's Estate Side Quest and ask you to go inside the building to kill a bunch of Dopplegangers. Sunin's House has Sunin, a mage whom you can kill for another Ring of Evermemory.
AR1200 (Baldur's Gate South): The Iron Throne Headquarters are in this portion of town which you will visit twice during the main story. Low Lantern is also found here which is boat that acts like a mini dungeon with multiple floors and a few encounters. To the south of the Iron Throne Headquarters you'll find a house with a blue roof that also has an encounter inside, this time 5 Ogre Mages. Water Queen's House/Temple of Umberlee is also found here and part of the Tremain's Son Side Quest. Just outside of the Water Queen's House you'll also find Gauntlets of Weapon Skill inside of a crate. The last important building here is the Harbor Master's Building which is involved in the Save Duke Eltan Side Quest during Chapter 7.
AR1300 (Baldur's Gate Southeast): A few side quests can be found in this section that will reward you with some EXP. Basilisk on the Loose is an easy one and you can complete G'axir the Seer immediately after with the Sphene Gem you get from the Basilisk. Arkion and Nemphre (picked up in Sorcerous Sundries) or Arkion's Bloodstone Amulet are both easy enough too. One of the generic houses has 2 thieves, Tavex and Michael whom you can fight for some EXP and items.