The ruins of Machu Picchu were discovered in 1911. Terraces built for farming and an aqueduct that brought water from a mile away helped sustain its ancient residents.
Gary Dean Anderson designed the recycling symbol in 1970, reminding us to recycle, reduce and reuse our natural resources. Without recycling, the average family creates one ton of garbage each year.
Green technologies are changing the world. Civil engineers are leading the way by designing systems and structures to support cars and other kinds of transportation that use alternative energy sources.
Communities are going green in many ways - planting rain gardens, and bioswales, building green walls and roofs, and using rain barrels to conserve water and control water run-off to name a few.
Photos courtesy of: Machu Picchu - ThiagoBeleza on FlickR; recycling - epSos.de on FlickR; alternative energy - Cores de Cima on FlickR; green communities - chesbayprogram on FlickR