Observatory

The Portland Observatory was built in 1807 by Captain Lemuel Moody to serve as a communication station for Portland Harbor. Portland Observatory was one of the earliest marine signal stations in the United States, and it is the last known to survive. The Observatory's location on Munjoy Hill gave it a clear view of vessels approaching Portland Harbor. The Observatory contributed to the prosperity of Portland Harbor as a vital center of maritime commerce during the "Golden Age of Sail."  

The Arecibo Observatory has the largest radio telescope ever constructed. Maintaining the greatest electromagnetic wave gathering capacity of any telescope, it has been an essential tool in modern astronomy, ionosphere and planetary studies. Several feats of mechanical engineering went into the construction of this observatory, most notable of which is a drive system which allows all active parts of the antenna to be kept focused with millimeter precision regardless of environmental factors—such as thermal expansion.

The increased light-grasp of this telescope made possible many notable advances in structural cosmology between 1924 and 1930, which have revised our ideas about the universe. One of these advances was that spiral nebulae are galactic units like our own; another was the idea of an expanding universe. George Ellery Hale began planning this project in 1906; Francis G. Pease was the chief designer and mechanical engineer. The telescope's mirror support and the use of mercury flotation to reduce the friction are among its outstanding mechanical engineering features.

Machu Picchu represents the culmination of Inca public works building standards and technology, as well as 4,000 years of Andean community development.  This landmark is the most well known archaeological site in South America and serves as a destination site for world travelers.  It was a royal estate for Emperor Pachacuti.