Ever since the discovery of the cave, humans have made use of nature’s geological formations. Only recently, however, have developments in structural engineering made it possible to engage the earth’s surface as a building element in its own right. With an increasing awareness of our planet’s limited natural resources, the most acclaimed architectural practices from around the world are building into the earth and merging man-made forms with the contours of the land. From Zaha Hadid’s Tram Terminal in France to Snøhetta’s Bibliotheca Alexandrina in Egypt, from Future System’s hill-burrowing house in Wales to Antoine Predock’s Spencer Theater in the United States, over fifty projects displayed here expose the breadth and depth of this new direction in architecture.