The "Cuatro Torres Business Aeria" or as it is reffered to by many: Madrihatten or Madridhatten. At the time the photo was taken some of the towers were still under construction.

Note on quality: this panorama is slightly bellow my quality standard. I didn't have my pano head with me in Spain to keep the camera still while rotating it, and due to the rail I had to make some compromises while stitching.