Q: Which famous buildings were named after a form of food - or was it the other way around?
A: The pyramids. The ancient Greeks used the word "pyramid" both for the Egyptian pyramids and to a kind of cake made out of roasted wheat. It appears that when the Greeks went to Egypt, they gave the buildings this name because they were shaped like the cake. (Some argue it was the other way around, but that wouldn't be so interesting.)
Source: Steven Schwartzman, The Words of Mathematics, Mathematical Association of America, Washington DC, 1994.
The 1970 Encyclopaedia Brittanica is more cautious:
The ancient Egyptian term for pyramid is mer. The English word pyramid comes from the Greek pyramid, plural pyramides, a word of doubtful etymology that was thought to have been derived from the ancient Egyptian per-em-us, a term used in a mathematical papyrus to denote the vertical height of a pyramid. A purely Greek word pyramis means "wheaten cake", and a vague resemblance in shape may have prompted early Greeks to use it as a facetious designation of the celebrated Egyptian monuments.
For more fun try these: