An Observatory is a building or satellite designed and equipped to observe astronomical phenomena. 

• Ground-based Observatories, located on the surface of Earth, are used to make observations in the radio and visible light portions of the electromagnetic spectrum. Most optical telescopes are housed within a dome or other similar structure in order to protect the delicate instruments from the elements. Telescope domes contain a slit or other opening in the roof that can be opened during observing and then closed when the telescope is not in use. In most cases, the entire upper portion of the telescope dome can be rotated in order to allow the instrument to observe different sections of the night sky. For optical telescopes, most ground-based observatories are located far from major centers of population in order to avoid the effects of light pollution. ^[1]
  
  
• Radio Observatories encompass radio telescopes, or a collection of them, with outbuildings for such things as control centres, data reduction centers, and maintenance are called radio observatories. Radio observatories are similarly located far from major centers of population in order to avoid electromagnetic interference (EMI). But unlike optical observatories, radio observatories will be placed in valleys to further shield them from EMI. Radio telescopes usually do not have domes. ^[1]
  
  
• Space-based Observatories are telescopes or other instruments that are located in outer space, many in orbit around the Earth. Space-based observatories can be used to observe astronomical objects at wavelengths of the electromagnetic spectrum that cannot penetrate the Earth's atmosphere and are thus impossible to observe using ground-based telescopes. ^[1]
  
  

A Telescope is an arrangement of lenses, mirrors, or both that collects visible light, allowing direct observation or photographic recording of distant objects. A refracting telescope uses lenses to focus light to produce a magnified image. Compound lenses are used to avoid distortions such as spherical and chromatic aberrations. A reflecting telescope uses mirrors to view celestial objects at high levels of magnification. Most large optical telescopes are reflecting telescopes because very large mirrors, which are necessary to maximize the amount of light received by the telescope, are easier to build than very large lenses. Radio telescopes are used to detect and observe distant objects by collecting radiation other than visible light. ^[2]

Take the "Around the World in 80 Telescopes" tour of
world-wide observatories and telescopes
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