All squares are rectangles, but not all rectangles are squares

Homes that old also have a bit of settling, I've yet to cut a perfect rectangle of a door.  

They do have some options for building up (see three story image below) but we created an apartment that consists of studios units, in the standard 16x74 foot modular home rectangle.

I have seen some that look great but there is no way to get around the look of a big rectangle stack.Personally I think the risk could be worth it if it was a bit more rural.

Then you pay a glass company to cut you a rectangle of glass for your 1/2 shower wall, and you're done. 

In both, our property is represented by a yellow rectangle.

I drawn up a site plan , looks like the 10k sqft building will fit, the land is flat and almost rectangle, with set back and required landscape, I still have 52+ parking.I plan to build and hold on it, as a steady income for retirement,  maybe use one or two unit by myself, as my wife always want to try a coffee/ice-cream/yogurt  shop. 

@Grayson Lynum Regarding Modular, I have gone down that rabbit hole several times, and what I found it, they are not cheaper, just faster, and they look like a modular, due to the transportation limitations, the rectangle box or Prow front on mods tend to have a stigma to buyers, also many of the finishes are very low end. if you site built a very basic rectangle with the same cheap finishes most mods come with, you will be financially better off. and they are not faster, typically from order to occupancy is 6-9 months, I did my last spec in 7 mo. its just not as much work on site, the time is waiting for the factory to get to your build. good luck!

Do your layout and talk with those trades.Example:Lets assume you do just one road with two entrances, one at each end.  20 acres if a rectangle is 1,320 feet long. 

Since your building just looks like a plain rectangle and is essentially a shell just find pre-existing plans online that match your building dimensions and use them.4.