Here are the Seven Wonders of the Ancient World:
The Great Pyramid is the only Ancient Wonder that does not require a description by early historians and poets for us to know about it. Its appearance, size, and shape are known (unlike the other six). Ironically, it is the oldest, yet only surviving of the Seven Ancient Wonders.
The Gardens may have only existed in the minds of Greek poets and historians. Supposedly, it was a palace with legendary gardens built on the banks of the Euphrates river by King Nebuchadnezzar II
Dedicated to the goddess Diana, construction began about 555 B.C. It burned down in 356 B.C., but it was rebuilt by Alexander the Great.
"In his right hand a figure of Victory made from ivory and gold. In his left hand, his scepter inlaid with all metals, and an eagle perched on the sceptre. The sandals of the god are made of gold, as is his robe." - Pausanias the Greek (2nd century AD)
Like the Great Pyramid, it was the burial place of an ancient king. Its sculptured friezes apparently made it a thing of great beauty, and likely led to its inclusion on the list.
Between its building and destruction are a mere 56 years (an earthquake snapped the statue off at the knees). Why was it included? This quote from Pliny the Elder - "But even lying on the ground, it is a marvel," suggests why.
The Lighthouse of Alexandria is the only one of the Seven Ancient Wonders to have had a practical use. It was the tallest building on Earth during its existence. It is believed that the mirror's reflection could be seen more than 35 miles off-shore. And the remains could be seen as recently as 1480.
Some of the facts come from this excellent site. It's some fascinating stuff!