Figure 1: The new site in the Congo [Source].
The image of the area shown in the BBC page reminds me a lot of the Manicouagan Impact Crater in Quebec. It's a striking feature from a few thousand feet up, with a diameter of around 60km - about twice the size of the Congo ring.
Figure 2: Manicouagan Reservoir as seen from [Source: Google Earth]
You can learn more about these and other impact sites at the Earth Impact Database, and can explore them here, via google maps.