• The Pyramids of EgyptSphenks at Giza Egypt image by TekinT from Fotolia.com
  
  Of course, any list of the "greatest" monuments in the world is a highly subjective endeavor. A number of such lists exist for both natural and man-made "wonders" and, while they do not agree on every item, a few monuments appear on nearly all the lists out there and are worth special mention--the Empire State Building, the ruins of Machu Pichu, the Pyramids of Egypt, the Taj Mahal and the Roman Colosseum among them, each a monument to the cultures that built them and the great triumphs of human architecture and engineering.
  
  

The Pyramids of Egypt (Great Pyramid of Giza)

• One of the seven wonders of the ancient world according to the Greek historian Herodotus, the Great Pyramid of Giza was the tallest man-made structure in the world for over 3,800 years. The pyramid is part of a larger complex containing two other large pyramids and several other structures and was built as a funerary monument to an ancient Egyptian Pharaoh whose tomb was placed inside the pyramid. Most archaeologists believe the pyramid was built around 2500 B.C.
  
  

The Ruins of Machu Pichu

• Located in a dramatic mountain setting above a steep river gorge, the ancient Incan city of Machu Pichu in Peru is perhaps one of the world's best known ruins. The city includes a number of impressive buildings that exhibit fine Incan masonry and, due to its abandonment just before the Spanish conquest, is remarkably well preserved. Machu Pichu was chosen as one of the "New Seven Wonders of the World" in 2007.
  
  

The Empire State Building

• Chosen as one of the seven wonders of the world by the American Society of Civil Engineers, the Empire State Building was the tallest structure in the world for over 30 years and the first building to have over 100 floors. The 1931 New York City skyscraper still has a commanding presence in the highly developed Manhattan skyline, and its unique style has been highly influential in modern skyscraper construction throughout the world.
  
  

The Taj Mahal

• A perennial favorite in traveler's top-ten lists and global architecture reviews, the beautiful Taj Mahal in Agra, India, was built by the Mughal Emperor in the 17th century as a funeral monument for his beloved wife. The central domed building houses a series of royal tombs decorated with intricate Islamic calligraphy, and the monument is surrounded by a set of tall symmetrical minarets.
  
  

The Roman Colosseum

• Also included in the 2007 list of new wonders (all chosen through an open global vote), the Roman Colosseum is one of the most recognizable buildings of the ancient world and the largest amphitheatre ever built in the Roman Empire. Completed in 80 A.D. with capacity for over 50,000 spectators, the Colosseum also featured an elaborate underground network of tunnels and rooms to hold gladiators and wild animals before each event.