The Ideal City.

That's "The Ideal City" by Fra Carnevale, c. 1480–1484. 

This post was created to front-page something that appeared after the fold on another post today, so if you care about context, read through to the "FROM THE EMAIL" section of the post that went up at 7:09 a.m.

I like it out of context too. The image itself seems out of context — idealized.