Today, people usually say thank you by writing a thank-you note.
The people of the island of Rhodes went way beyond that. The islanders survived a long siege by the mighty Macedonian army in 305 B.C. Afterward, they decided to build a giant statue of Helios, the Sun god, to give thanks. It took them 12 years, from 294 to 282 B.C. As tall as an 11-story building, it towered over the harbor. This statue became known as the Colossus of Rhodes.