The Idea is to post a comment on the previous floor made, and then to describe a new floor of our skyscraper. The laws of physics need not be followed. Please specifify which elevators can access each floor you build.

I’ll start.

Floor 1: The lobby

this room is a single marble room with a receptionist’s desk front and center on entry. The half-ork receptionist knows the floor number of everything in the building, and has a desktop computer. On all other walls are elevators, each with a list of floors it can access. There are 6 elevators, 1-3 on the left, 4-6 on the right. The elevator doors are made of marble. 

Rumor has it, if you take elevator 4, specifically elevator 4, you can reach floor 3. Floor 3 looks like a normal city, a city within a hotel. Nobody goes to floor three(well almost nobody, we'll get to that in a second), in fact, the receptionist denies the existence of floor three, however, if you go to elevator 4 at exactly midnight, you will be met by a drow man. he knows many things, and he will tell you that floor three is real, but those who go to floor three come back changed. Nobody can tell what that change is, but it's there. Perhaps this floor is another realm, perhaps elevator floor is a portal. Who knows? Definitely not the receptionist or the drow man. The drow man does not share his name

The next floor on our mystical magical fantasy skyscraper is floor 4, which can be accessed by asking the creepy old man standing in the corner of the lobby to take you there, in which case he will teleport you there for exactly 17 minutes before you teleport back to the front of the skyscraper. The room itself is a Fananese (Basically Japanese, but fantasy) themed room with a person in the middle that makes everyone who enters the room play a definitely not rigged shell game that costs 5GP, with the reward being 5GP and 1SP. Everyone who enters leaves with their wallets much lighter.

Edit: I like this game, it's not weighed down by having to do something relating to the previous post, keep it up

Floor 5 is accessed by a seventh super secret service elevator intended for servants only. When you enter for the first time, you are dumbfounded. It is a magical resort with a volleyball court, a hot tub and Olympic pool, a forest that stretches farther than the eye can see, and a bar. (Of course there's a bar. There are always bars in magical skyscrapers with Half-Ork receptionists.) Right now, a dragon beauty pageant is being held to determine the winner of 'Ms. Waterdeep.' (Like Ms. America, but Waterdeep. Because dragons) Upon hearing of the winner, a Green dragon named Oolalalalalalaga, the losers stormed the stage. You run for the elevator as hail, fire, poison, acid, and lightning spew from the battling contestants' mouthes, devastating the picturesque landscape. (Oolalalalalalaga is proving that she is more than capable of defending the Ms. Waterdeep title.) As you rush into the elevator, the doors close and your companion, the Half-Ork receptionist who has finally left his desk, sighs. "This is pretty much a normal Tuesday."

The elevator marked "elevator 2" is covered with out of order tape and seems to not be functioning. Pressing the button, however, causes it to sputter into action and open up, and will take the user to floor six upon request.

Floor six itself is very curious, as it consists of six gothic stairwells, some steampunk furniture, a bed of petunias, and a single modern office space. The mind flayer working it, Joe, will say that each staircase leads to another elevator, each marked 7 to 12. He will then continue to take calls addressed for one Mr. Phil Morty.

Floor 7 is accessible through all of the elevators, even the invisible ones. It is a row of toilets, stretching as far as the eye can see, and then some. They are all glistening white, perfectly polished and scrubbed. Even as you watch, Joe the Mind Flayer accidentally 'soils' one of them with a deep brown stain, and the stain instantly disappears. Of course an infinite line of self cleaning toilets is part of our magical skyscraper. I haven't heard the loos mentioned on any other floors. :D

Floor 8 is also accessible only by flushing one of the toilets on floor seven, at which point you are instantly teleported to floor 8. Here is an infinite line of sinks, but this time they are all stone basins, somewhat contrary to the polished white of the toilets. As you watch, Joe the Mind Flayer appears in a cloud of smoke, and begins washing his hands in one of them. Paul the orcish janitor is working on the pipes of one of the sinks, and a goblin named fred is battling a strange slime monster that appears to have come from one of the sinks. A yuan-ti with a Hello my name is... sticker by the name of Awesome can be seen installing new porcelain sinks nearby. "We're still in the process of going modern," he says, tightening a screw, and instantly every sink becomes porecelain. "Aaand now we are modern," he says. Just then, probably but not certainly by coincidence, the goblin beats the slime monster into a trash can using an old broom handle and the orcish janitor is hit by a spray of water by the brand-new sink. Joe goes back into the elevator, presumably back to floor 6 to continue taking calls.

Floor 10 is an... unusual experience, to say the least. To access the floor, one must roll an icosahedron on the floor of the 7th elevator and have it land on the '20' side. It is a room full of desks, with vague humanoids throwing around small cubes, pyramids and prisms and scribbling in notes behind screens, speaking in hundreds of voices. You are hit with a strange sense of deja vu from the voices... I wonder why?

(Yes, that is the technical term for the D20)

Floor 11 is a giant 7-11, available only if you jump into Willy Wonka's glass elevator (aka elevator #6). The elevator opens, and you see sahaguin sipping on Slurpees, orcs scarfing down ice cream, and mind flayers buying lotto tickets. In the middle of it all, you see a Spectator with a name tag that says HELLO, MY NAME IS IMMA GONNA RIP YOUR FACE OFF manning the cashier. He glances up with a bored expression, sees you, and quickly zooms into the elevator before you can stop him, or even get a Slurpee. As the doors close, the orcs realize that the only employee is leaving, and they proceed to raid the cashier. The last thing you can see before you zoom on up to the next floor is a mob of orcs making it rain stolen cash. 

Floor 12 can only be accessed by the 12th elevator at exactly midnight, and only if Joe the Mind Flayer puts his key in the emergency fire keyhole. The elevator door opens to a glass box which seems to be floating in the middle of a city shaped like a ring. There in the middle sits a man named Mr. Phil Morty (Yes, Mr. is his first name.) As you enter, the man greets you and shows you around his office. Behind his desk sits a chessboard, which, when he moves a piece, seems to control where the box moves. Opposite of Mr.'s desk is a full array of news cameras, all pointing at his face. As you leave, again by elevator, you hear an echoing voice boom "ACTION!"

I also like how only one floor so far has a straightforward way of getting to it.

To access Floor 14, you must shoot five different elements into five large holes in the back wall of the skyscraper, you will then pass out and wake up in Floor 14. Floor 14 itself is an extremely large bedroom, that houses none other than Tiamat herself (Herselves?), usually seen sleeping or working, but there is a very rare chance that she is somewhere else, leaving her treasure pile, which includes over 100 Deck of Many Things’s, and a similar amount of Bag of Holding’s, guarded by only a single Tarrasque, what a steal! To leave you... Don't... Or rather, can't, even through such means as a Teleport or Plane shift spell, you simply stay right where you are, though there is one powerful drow wizard named ”S. Pell” that managed to get out alive, though she wouldn't disclose how.

To access floor 16, your age must end in 16, it must be the 16th day of the 16th month (remember it’s fantasy), and the time must be 16:16 (military time), then you may enter floor 16 by taking, go figure, the 16th elevator. The floor itself is a library with 5 shelves, but no books, instead, you must reach your hand towards one of the shelves while thinking of a book, or a topic a book might contain, then a book that fits that description will materialize where you are reaching towards. Another oddity about this floor, is that time itself ceases to function while on this floor, meaning that when you enter at 16:16, no matter how long you wait, when you leave the floor, the time will still be 16:16, and you will remain the same age no matter how long you wait. To get out, you must simply think about leaving, causing you to instantly leave, no matter what you were thinking about, as long as in contains something leaving this floor, you are immediately escorted out of the floor by a Beholder named ’Gkjddwjewjnwedkkpfvw’, ’Gekej’ to his friends.