Abandon buildings and ruins offer a great scope for interesting shots, due to the way the lighting falls through nooks and missing glass windows. Peeling paint and rust offers a wonderful variety of textures and multi layering of colours given the weathered objects a sense of history and passing of time.

Abandon building also enable you to create a sense of wonder, a story of what has and might have gone before, once a living thriving place but once again subject to erosion and natures continual touches that make it still seem alive and captivating.
Things to look out for are:
Windows and door create great framing for photos and can capture natural light falling through it
Passageways
Details - peeling paint, rust, keyhole, door handles