What is the largest confirmed impact structure on Earth?

Also known as the 'Vredefort Dome’, the Vredefort crater has an approximate radius of 190km (118 miles), making it the world's largest known impact structure. What remains of it is in the present-day Free State province of South Africa. The crater was named after the town of Vredefort, which is near its center.

Although the crater itself has long since been eroded away, the remaining geological structures at its center are known as the ‘Vredefort Dome’ or ‘Vredefort impact structure’. The crater is calculated to be 2.023 billion years old, with impact being in the Paleoproterozoic Era. It is also the second-oldest known crater on Earth, after Yarrabubba crater.

In 2005, the Vredefort crater was added to the list of UNESCO World Heritage Sites for its geologic interest.