If you google search on these images this comes up:
The Neptune Memorial Reef
Located 3.25 miles east of Key Biscayne in Miami, Florida – GPS coordinates N25º 42.036’, W80º 05.409’ – Neptune Memorial Reef™ is the largest man-made reef ever conceived and, when complete, will have transformed over 16 acres of barren ocean floor. Our completed first phase is a classical re-creation of the Lost City, 40 feet under the sea. These structures have produced a marine habitat to promote coral and marine organism’s growth while creating the ultimate ‘Green Burial’ opportunity.