Every single building is a rejection of entropy. We're literally carving out a secure and comfortable space for ourselves to exist inside. It's literally built to withstand and reject the elements, the chaos of the outside universe. Even the stereotypical jungle survivalists create structures to bend the surrounding environment to their benefit instead of allowing them environment to bend them. Structure is the antithesis of entropy.

This is entirely orthogonal to economically efficient concentration. In fact, cities are an extension of it. We want to be safe and comfortable when we leave the buildings too. We don't want the cities to just look nice, we want architecture that makes our very souls feel safe and protected. We want facilities like well maintained sidewalks and roads so we can walk and drive with ease. This leads to economic efficiency.