Vredefort Crater - Asteroid impact date: Estimated 2 billion years ago. Location: Free State, South Africa. Also known as the Vredefort Dome, the Vredefort crater has an estimated radius of 118 miles (190 kilometers), making it the world's largest known impact structure.
Vredefort Dome, approximately 120 km south-west of Johannesburg, is a representative part of a larger meteorite impact structure, or astrobleme. Dating back 2,023 million years, it is the oldest astrobleme yet found on Earth. With a radius of 190 km, it is also the largest and the most deeply eroded. Vredefort Dome bears witness to the world’s greatest known single energy release event, which had devastating global effects including, according to some scientists, major evolutionary changes.
The oldest impact crater on Earth is also the largest. Vredefort crater in South Africa, also called the Vredefort Dome, was originally 185 miles (300 kilometers) across, scientists estimate. A meteorite or asteroid bigger than South Africa's Table Mountain blasted out the giant crater 2.02 billion years ago.
Big Boom: The Best Places to See Meteorite Impact Craters - Ancient impacts changed landscapes and perhaps even the course of evolution—here's where to see the coolest craters this summer. Tthroughout history, meteorites have left their beautiful—if destructive—scars upon the globe. Here are some of the best places to see meteorite impact sites this summer: Barringer Meteorite Crater: Arizona, Vredefort Crater: South Africa, Wolf Creek Meteor Crater: Australia, etc.
Young earth v. old earth: If this had happened sometime within the last 6,000 years, I kind of think it would have been noticed. :) "The multiple-ringed Vredefort Crater - The asteroid that hit Vredefort is estimated to have been one of the largest ever to strike Earth (at least since the Hadean Eon some four billion years ago), thought to have been approximately 5–10 km (3.1–6.2 mi) in diameter. The bolide that created the Sudbury Basin could have been even larger."