"Vertical Landscape" by Eiko Ojala. It looks like a paper landscape but the artist actually works digitally and hand-draws all the elements to look like they're cut out of people. (Hint: the shadows help!
Peter Eisenman's Berlin/Holocaust memorial Light and Shadow. I like the way the structure of the building creates strong impressions of light and dark. Also the juxtaposition between the natural and man-made forces interests me.