[adolph]

Your reasoning is well taken and haven recently read Hofstadter's "Surfaces and Essences" the idea of what is a thing and what is not is fascinating.

Some of the criteria are questionable to me. For example, some monuments or memorials are still buildings, such as a mausoleum. Would your survey respondents deny a mausoleum is a building?

I could also ask myself, would I consider the Statue of Liberty a building? It is in active use; it has some usable interior volume; it is free-standing above the surface. And yet I hesitate to call it a building more than I hesitate to agree a lighthouse is a building.

[poulsbohemian]

Without exploring etymology, what strikes me as interesting here is that buildings are generally structures in which we live or work. Mausoleums and pyramids are interesting in this regard because they are the opposite: they are places for the dead. Perhaps it is this use rather than the actual form that is cause for debate in the description of building, given that a building can take so many forms even in our agreed definition of the term.