In the 1940s, archaeologists discovered the ancient city of Seuthopolis, the capital seat of the Odrysian Kingdom beginning in the 4th century BCE.
Unfortunately, the discovery came too late, because under construction nearby was a reservoir dam, which would soon flood the valley and drown “the best preserved Thracian city in modern Bulgaria.”
Now over half a century later, a project proposed by Bulgarian architect Zheko Tilev would uncover and preserve the ruins using “a circular dam wall, resembling a well on the bottom of which, as on a stage, is presented the historical epic of Seuthopolis.”
Indeed, most everything about the project is theatrical: “Approaching the surrounding ring by boat from the shore Seuthopolis is completely hidden for the eye. But the view from the wall is breathtaking - with its scale, comprehensiveness and unique point of view; from the boundary between past and present. The possibility to see the city from the height of 20 meters allows the perception of its entirety.”
Once there, and if your interest in exploring archaeological sites wanes considerably faster than expected, there are other things to do on the ring-wall. For instance, there will be restaurants, cafes, shops, bike rental facilities, and also other facilities for various recreational sports and fishing.
Programmed as “a unique modern tourist complex,” the ring-wall will also house a museum, a hotel complex, open-air exhibitions, concert and festival halls, conference centers, and hanging gardens.
It's a classic case of horror vacui, in other words.
There are three sites where this should be done as well:
1) New Orleans (i.e., having abandoned the city, its inhabitants now live and work and die on grossly heightened and fattened levees; everyone will laugh at them, but when the deluge comes, they will have the last laugh)
3) Yonaguni (i.e., if it's actually manmade)
POSTSCRIPT #1: For a different strategy than the one planned to uncover and preserve the ancient city of Seuthopolis, see the planned underwater museum of Alexandria.