This is a picture of the Burj Khalifa, the tallest building in the world located in Dubai, photographed by the GeoEye 1, the highest resolution commercial imaging satellite. Impressive!
Now, there are probably spy satellites out there that can zoom in much farther and with much greater clarity, but for us plebes, the GeoEye 1 will have to do. Here are its details:
GeoEye 1 is at an altitude of 684 kilometers over the surface of the Earth, and it's capable of capturing details of just 16 inches long in black and white, and 64 inches in color.