Which capital city is closest to the equator?
And the answer: Quito.
Located just 25 kilometers south of the equator, Quito is the capital of Ecuador (which gets its name from "equator"). Quito is also the oldest South American capital, and the second highest capital city in the world.

Quito is a scenic and historic city with a rich and diverse culture. Named for the Quitus tribe that occupied the area in first millennium, Quito is widely believed to be one of the oldest (if not the oldest) continuously inhabited settlement in South America. The Kingdom of Quito was officially founded in 980 BCE by the Cara or the Schyris people, who came in from the coast to lay claim to the land. By the time the Spanish had conquered the region in 1541, Incan influence had created a massive, bustling city out of Quito. It's rumored that the Spanish chose Quito as the site for their capital because they sought buried Incan treasure said to lie beneath the city.

The Spanish capitalized on the infrastructure created by the Incans and added to it, with countless buildings in colonial styles throughout their new imperial acquisition. The Spanish went on to rule the city for over 300 years, until Quito finally gained independence in 1822 with the help of Simón Bolívar.
Quito lays claim to a number of geological and architectural wonders. The city was named the first UNESCO World Heritage City due to its extensive and well-preserved history of Spanish America, and also takes first place as the world's highest constitutional capital. Today the city is a bustling and gorgeous intersection of history and culture, and due to its proximity to the equator, enjoys some of the most sunlight of any capital city in the world.
Learn more about Quito here.
