At least 35 small pyramids, along with graves, have been discovered clustered closely together at a site called Sedeinga in Sudan.
Discovered between 2009 and 2012, researchers are surprised at how densely the pyramids are concentrated. In one field season alone, in 2011, the research team discovered 13 pyramids packed into roughly 5,381 square feet (500 square meters), or slightly larger than an NBA basketball court.
Source: Live Science. Read full article. (link)