1.Gustave Eiffel (www.greatbuildings.com/buildings.html)

2.Sears Tower-1700 feet (www.searstower.org)

3.The soil was not strong enough to hold the weight of the tower (torre.duomo.pisa.it)

4.23,000 (www.defenselink.mil/pubs/pentagon)

5."El-Ahram" (www.delange.org/Gisa_Pyramids_Sphinx/EP3.htm)

6.The Great Wall of China (www.enchantedlearning.com/subjects/greatwall/allabout.html)

7.Three Gorges Dam (www.itvs.org/greatwall/

8.Groom Lake Base (www.Area51zone.com)

9.Mount Rushmore (www.travelsd.com/parks/rushmore/index.htm)

10.Pearl Harbor (www.execpc.com/~dschaaf/theday.html)

11.Liberty Island (www.endex.com/gf/buildings/liberty/liberty.html)

12.Kuala Lumpur, Malaysia (www.infoplease.com/ipa/A0001338.html)

13.A deep subterranean supply of water,a source of heat, and fissures (www.oldfaithfulgeyser.com)

14.The Berlin Wall (userpage.chemie.fu-berlin.de/BIW/wall.html)

15.Buckingham Palace (www.royalresidences.com)

16.Africa (www.saharamarathon.org)

17.The Mackinac Bridge (www.greatlakes.net/teach/history)

18.Ginko Petrafied Forset State Park (htpp://students.washington.edu)

19.2555-2532 B.C.E (www.geocities.com/athens/delphi/3499/sphinx.htm)

20.Wrigley Field (lb.com/NASApp/mlb/chc/ballpark/chc_ballpark_history.jsp)