...the Porter Garden Telescope. Russell Porter was an artist, engineer, and amateur astronomer/telescope maker, and in the 1920s in Springfield, Vermont he made some number (at least 53, according to the highest serial number found, but the exact count is unknown) of what must surely be the most beautiful telescope ever manufactured, designed specifically for the garden. Only 14 are known to survive, one in the Smithsonian museum.
Porter combined all he knew of art and science in an art nouveau style masterpiece made like an unfurling flower with a mirror at its heart. The bronze housing was designed to remain outside, mounted on a plinth like a traditional garden sundial (if oriented correctly it could in fact operate as one) and the optical components were removable, to be used for viewing biplanes and other heavenly apparitions if the weather was fair and kept safely inside if not.
[Period images are from stellafane, the home of Springfield Vermont Astronomy, which owns several of the original Porters. They are seeking the watercolor (second image above), which was stolen from their collection. Modern photos are from Edmund optics, who provide the optical components for the reproduction telescope. Images of one of the original garden telescopes can be seen at a fansite here]