What are the seven wonders of the world? Why were they chosen?

The seven wonders of the ancient world include the following:
the Pyramids of Giza, 
the Hanging Gardens of Babylon,
the Temple of Artemis at Ephesus,
the Statue of Zeus in Greece, 
the Mausoleum of Halicarnassas,
the Colossus of Rhodes and
the Lighthouse of Alexandria.
Only one of these, the Great Pyramid of Giza, still survives. (Some historians say the Hanging Gardens never really existed.) All seven wonders were chosen as works of architectural importance that were those most often commented on by ancient travelers who wrote about their journeys. Since most of the writers were Greek or Greek speaking and from the Middle East or Mediterranean area, they focused on structures in that area, and emphasized Greek accomplishments: five of the seven wonders (all but the pyramids and the Hanging Gardens of Babylon) are Greek.