We moved in to our current house a little over two years ago. One of the first things I did was start building a cellar. At our previous house I had a passive cellar that was very simply constructed, at this house I decided to do a little more but still keep it relatively simple.
A portion of the old cellar

When we sold the house there were a few more cheaply constructed units built, total capacity of about 300 bottles. (I am not sure why this picture posted upside down)
The new cellar has official capacity of 400 but there are closer to 700.

The left side

The four to six bottle gaps on the left are for Becklyn and Myriad which should be arriving shortly.
The right side

Match up the bottles of Belle Glos (one of my wife’s selections) to get a better feel for the small size of the cellar.
The “deep cellar”. This is an area under the stairs that was sealed off when we bought the house, we thought it a shame not to utilize it. Over Thanksgiving I will build another rack on the left so the bottles are not simply stacked, they are hard to access right now.

I am 5’-4" and pretty fit so while this area is only about 36" tall and looks inaccessible, I can fit nicely.
We use a CellarPro 1800 XT to cool it. I have a Wireless Tag system to monitor it.
I framed, insulated, wired and sheetrocked it myself, though my wife helped me do the ceiling sheetrock. I finished the sheetrock myself but had someone else paint it as I hate painting. The flooring is floating cork. The light is on a timer and dimable. I have some finishing touches to do, a little trim here and there and I am going to build racking for 375’s, mainly Sauternes. I also want to leave room for a few glasses and a decanter.
Overall it is a ver compact space but it works for us. My wife had limited my to 365 bottles in stock but that went out the window when we sold the previous house and I knew I would behave more room in this one. In a way I would like a larger and nicer cellar, this one suits us well and I can afford to overstock it.
Along with storing chocolate and Nola’s olive oil, my wife sometimes stores fruit in the cellar. I am ok with anything other than peaches, I can’t stand the smell.