1. Only old structures made for agriculture will be accepted. Elevators and cement/Metal silos. Commercial or ranch/farm silos OK.
2. Include a brief history if possible for interest of all; searching a particular sentinel online will bring up lots of info.
3. Location of where the sentinel is located is appreciated.
4. No excessive photoshop images please! Try and use the natural lighting, tones and textures to gain the desired effect. Some HDR is okay. All media is accepted.