The Octan Tower is a Realm in The LEGO Movie, and Lord Business's lair. As its name suggests, it is a large office tower-like building that is the headquarter of the Octan Corporation. The Infinitieth floor of the Tower is actually a detachable module and the holding place of the Kragle throughout the film's duration.
A lot of stuff happens here near the end of the movie.
After the attack on Cloud Cuckoo Land, Emmet and his team hatch a plan to Break into the Octan Tower.
The first part of the plan involves Emmet and his team building an Octan Delivery space ship to bypass the Laser Gate.
Benny and MetalBeard and sneak into the control panel room and try to disable the shield system, but Benny gets frustrated as he keeps failing to get the shield to disable, the computer finding movies, restaurants in Albania, and Where Are My Pants episodes.
Then the scene goes back, Wyldstyle leaves the scene to go do her part.
Batman gets his grappling hook ready while Emmet tells Benny to disable the shield, Wyldstyle fakes a call and Bad Cop leaves his position, Wyldstyle takes down the Robot guards and gives the signal.
Emmet and Batman get ready and Benny still can't deactivate the shield, then finally MetalBeard tries and disables it just in time.
They are then taken to the think tank and taken hostage.
Vitruvius tries to fight back but Lord Business decapitates him with a penny. However Vitruvius comes back as a ghost and tells Emmet that you are special if you believe you can be, knowing it sounds like a cat poster.
Lord Business leaves in the top piece of his tower and goes over Bricksburg and the realms.
This scene comes before Emmet comes into our world and discovers "The Man Upstairs" and his son Finn.
It has infinite floors, but there is a top. How this is possible, who knows.
It is its own realm in The Lego Movie Videogame, and it is in Bricksburg in Lego Dimensions.
To emphasize its scariness, there is a coyote howling at the bottom.