The Creeper Citadel is a magical place that can be accessed via a location in Central. Simply push the button, and you will arrive at The Creeper Citadel.
The Creeper Citadel on the Map
Moosemart is a place that contains traders to purchase a wide array of items including potent equipment enchantment books, science item trades, and neverending villager emerald trade ins.
Find your Post Office Box and see if your friends dropped anything off to you!
Accessed via a button in the courtyard, the Cannon will instantly shoot you to the Science area of your choosing. Only open on Event Night, so get your sciencing in every Saturday!
Speaking of Science!, take a tour of all the [Science] Items in the Cavern of Science. A vast chamber full of goodies, you'll want to explore this place when you have some time on your hands.
Get a copy of the latest Statues Book here! Also, if you are sitting on a bunch of levels you want to conserve for another time, trade them in for Bottles o' Enchanting.
On a small floating island, this is where one can turn in Horseman quest items. For a full description of the office, how to find it, and an overview of the Quests, visit this post.
The Masters of each Guild hold court in their wondrous golden Guildhall.