St. Louis is a major city in the state of Missouri, United States, located along the western bank of the Mississippi River. It is widely recognized for the Gateway Arch, which defines its skyline and reflects its historical role as a point of movement toward the western parts of the country.

Maui, both second youngest and second largest of the Hawaiian Islands, is home to the world's largest dormant volcano, Haleakala, meaning "House of the Sun." Last erupting about 200 years ago, it makes up the eastern end of the island. Maui was formed by volcanic activity from Haleakala on the east and the West Maui Mountains to the west. The connecting isthmus between the two spots was formed from joining lava from both and gives Maui its nickname, the Valley Isle.

Located on the north coast of Morocco near the Strait of Gibraltar, Tangier is a cultural capital replete with historic sites, colorful architecture, and splendid beaches. An essential stop is the Ancien Medina, a walled collection of winding streets and alleys filled with cafes and shops leading to the Kasbah, a former palace and mosque that also houses a museum.

Maseru, the capital of Lesotho, sits along the banks of the Caledon River near the border with South Africa. As the political and economic center of the country, it offers a mix of modern amenities, government offices, and bustling markets.

The Great Barrier Reef stretches along Australia’s northeast coast, forming the largest coral reef system on Earth and one of the planet’s most complex living ecosystems.