It may seem unusual for a photographer so obviously enamored of nature to seek beauty in human creations. But there is no intrinsic aesthetic conflict between these two realms. Both the natural world and the human world have much to offer visually to a careful observer, though any comparisons might be described fairly as apples vs. oranges.
Only a tiny portion of the full range of human creations is captured here, but its variation is substantial. This section goes from the urban canyons of New York City to an old sea captain's house on the Maine coast, and from the apparent conformity of a modern office cubicle farm to the unique home of one of history's most famously independent thinkers. The more mundane creations here serve basic functions, such as holding a cocktail or transporting people along a hallway. But at the other end of the spectrum are engineering marvels which have themselves attained the status of art works, such as the Brooklyn Bridge, I.M. Pei's East Gallery of the Smithsonian, the modern grand piano, and two famous 2008 Olympic venues. There is no unifying theme here, though geometry dominates several images. These disparate human creations are assembled here solely because they are eye-catching.
In one case, an unusual amount of Photoshop modification was applied. Because of its parallel vertical lines, the Cubicle City image appears to have been taken at the level of the windows. Yet the fact that you are clearly looking up at the office ceilings shows this to be untrue. The simple explanation is that the image was indeed shot from below, but was digitally modified to appear otherwise. The digital "correction" applied was exactly the same that any architectural photographer of decades past might have done optically using a perspective control camera.