Inspiration for maps?

In the context of this, I assume you are asking what inspires us to build maps in forge? If so, then here is my answer:

ANIME

That and music, pretty much it. I'm not really inspired by real life, but I do mimic it in my infection maps fairly well without inspiration, I kinda force it out like a turd while you're constipated. (gross analogy, )

However, most map makers (you know, the ones who are pro and actually do it for a living) base their maps off of something that has already been based in the storyline and the campaign of the game, or they go loosely off of predefined types of architecture used in the game and try to make something that is unique, so in other words, the story of the game they make the map for is their inspiration I believe. Now, I could be terribly wrong here being as that is purely hypothesis.

 

I'm thinking about the same field myself (though a ways off from it.) Inspiration really is a funny thing, it can come from anywhere or anything. I will give some examples, but I would say basicly do something you like to do, something that you enjoy.
My maps:
First Tracks- A ski resort that ascends three slopes for an original invasion experience. I got the idea from two sources; seeing a ski lodge map on forge hub and remembering a trip I took skiing a year before. This combonation led to a spark, which became a sketch, which became a build, which is actually still in refinement after about three months.
Tuscan- Playing Assassin's creed 2, I realised I wanted a map that was easily traversible between ground and roof fights. After sketching the idea, it just evolved into a crazy 2 v. 2 map that has been fun ever since.
In the end, inspiration is just something you find, whatever you love will bring it forth. Here are the links if you wanted to look at the maps, I was just rambling on, I don't get to talk about my design process much.
First Tracks (not current version): Bungie.net : Halo Reach : File Details
Tuscan: Bungie.net : Halo Reach : File Details

 

Something else that might help is developing a main theme for your map. One of the first maps I built was supposed to be a Forerunner adaptation of an oil-drilling platform. I built four towers, and then connected them, and started expanding them for non-catwalk-gameplay, and well... it sort of comes together! Not saying that's fool-proof, but like Flyingshoe said, inspiration from real life comes in handy.

If that doesn't work, you could always go to the Competitive section and scope out some successful maps. Not saying you should just rip out ideas from other peoples' maps, but some elements might make you want to build something revolving the idea, whether it'd be a place, or a design, or whatever!

And, this isn't really associated with inspiration, but it's quite helpful for the 'theory' of map-building, which you're probably going to want to look into if you're going to be a professional someday. ;D

[Forge Lessons on Bungie]

 

Some of the ways that I see maps made is that the maker starts with a random letter. From there, start deforming it (make it a symmetrical letter + deformation if you want a symmetrical map). Once you have your really twisted letter made, use that as your overhead layout. An example that I have seen recently is that the Gears 3 Beta map, Trenches, looks almost like a deformed W.

Other examples; try to make a backstory to the map or have something in real life to base your map on. I made a Halo 3 map called Luminary and it was based off of an archaeological dig-site; so of course, I had structures that look like they are half-buried relics. A mini-game map that I am about to post is Capture the Flag, but played like how most little kids (well...kid in my part of the world) play it- with 2 sides of a gym/soccer field, a midline and a jail for when people get tagged. I got the inspiration when my high-school gym class decided to play it.