The Taj Mahal, India

Top 5: The Taj Mahal, India

Located in Agra, Uttar Pradesh in India, the Taj Mahal is widely recognized as "one of the universally admired masterpieces of the world's heritage." It became a UNESCO World Heritage Site in 1983. However, this piece of "perfect architecture" is now under the threat of environmental damage, including soot, particulates and acid rain. The declining water level of the nearby Yamuna River is affecting the building's wooden foundation and both air pollution bas well as a heavy tourist flow have been ruining its walls. If no effective measures are taken, this architectural masterpiece may very well collapse in a few years.