Minecraft Story Mode:Portal Network

The portal network, referred to as a hallway by the protagonists, is a location created by The Old Builders that serves as a hub for portals into different worlds.

Layout
Portals in the portal network have different colors. Each portal has a "frame" made out of a material that represents the world this portal leads to. One wall contains a secret quartz staircase that leads to Old Builders if the redstone heart is placed inside of it.

Usage
The portal network was used by the Old Builders to travel between worlds. They've created an atlas to help them navigate between the worlds.

Portals

 * Sky City Portal
 * Spooky Mansion Portal
 * Crown Mesa Portal
 * Homeland Portal

Unnamed

 * Ice Portal (Jesse and the gang exit a portal covered in snow).
 * Gravity Portal
 * Sheep Portal (possibly a mob world)
 * Squid Portal (Jesse is seen running out of a portal with a squid on his/her head)
 * Dark World Portal (or just bat world or cave world)
 * Fire World Portal (a Nether-like world, Made of netherrack with a fire block and a gold outline in the shape of nether terrain)
 * Ocean World Portal (Jesse and the gang as see in glass helmet similar to Magnus the Rogue's helmet exiting the portal)
 * Sea Lantern Portal
 * A world with Chickens the size of Zombies.
 * A world with Zombies the size of Chickens.
 * Purpur Block Portal (Possibly an outdated small reference to the 1.9 Combat Update)
 * Pink Portal
 * Many others

Trivia

 * The Portal Atlas is the only known way to properly navigate the Portal Network.
 * If you enter a Portal of the same world you are in, you will land in the Portal Network.
 * Every portal has gold blocks integrated into or around it.