Let me try to put together a few ideas:

1. Americans tend to subscribe to the phrase “a man’s home is his castle” and all that means for a private home owner.
2. Plenty of Americans like McMansions, large homes with dubious architecture often found in sprawling neighborhoods or as much larger houses compared to their neighbors.
3. McDonald’s is a famous American brand and helped give rise to fast food that goes well with driving and the private single-family homes of suburbia.

Put these together and you have a McDonald’s in a castle in northern Indiana:

Only in America might someone build a gas station castle (it looks like a castle but in a McMansiony way) that contains a McDonald’s. I wonder if it attracts any more customers just because it is a castle.

(This building has apparently been around a while but I recently saw a story about it that caught my eye because I have seen other castle gas stations in other northern Indiana trips.)