The site is a small area in and around a building that is suspected of having been used a decade ago to test triggers for nuclear weapons.
Commercial satellite imagery from July 25 shows what appears to be the final result of considerable sanitization and earth displacement. 
Parchin, about 30 miles south of Tehran, garnered international attention in late February when the IAEA said it wished to inspect it as part of its tasking to ensure there had been no military nuclear activity by Iran.
Iran has consistently refused to grant the IAEA access to Parchin. It has insisted instead on allowing access only after the negotiation of a broader agreement addressing all issues concerning the military dimensions of its nuclear program. The IAEA agreed and attempted to negotiate an agreement. However, Iran demanded that the IAEA limit its inspection rights and methods, something the IAEA was not prepared to do.
To many, Iran’s negotiating strategy appeared aimed at stalling while it undertook the cleanup.
The site had sat unchanged from early 2004 until a month following the IAEA request for access when trucks, earth-moving equipment and other gear arrived.
Iran denied doing any clean-up, calling it routine construction work. The first signs of such activity were publicly reported by the Washington-based Institute for Science and International Security (ISIS) in May with satellite imagery shown here.
Over the subsequent four months there was considerable activity with the razing of two buildings within the site, notable earth removal and displacement, the likely sanding down and washing of the inside of the main building and possibly its exterior surfaces, the removal of the security perimeter, and the removal of all roadways.
The latest image, from July 25, shows stark differences in the site’s current layout from the first photo, taken April 9. The entire area surrounding the buildings appears to have been bulldozed, covered and flattened. There are no traces of heavy machinery or construction materials suggesting that no major activity is planned in the near future.
ISIS said, “The degree of the site’s modification and the fact that this apparent cleanup work started soon after the IAEA’s request for access cast further doubt on Iran’s claims that its nuclear program does not or has never had any military aspects. Notwithstanding its refusal to address the IAEA’s broad evidence and many questions about the possible past military dimensions of its nuclear program, Iran’s refusal to allow prompt access to the Parchin high explosive test site and the subsequent alterations bring into question its intention to clear up its nuclear case with the international community.”
ISIS argued that “unless Iran’s demonstrates concretely that it is willing to address these issues by the September IAEA Board of Governors meeting, the Board should pass a resolution that refers this set of issues to the UN Security Council for further action, including the imposition of additional sanctions.”