Pruned has a great find about the Bugarian lost city of Seuthopolis and Bulgarian architect Zheko Tilev’s proposal to uncover and preserve (pdf) the sunken city:

Seuthopolis, the city of the Thracian king Seuthes the IIIrd, and the capital of the ancient state of Odrissia, (end of IV c. BC.) was discovered and explored in 1948 – 1954 during the construction of the Koprinca dam. Unfortunately, after the dam was filled with water the first and the best preserved Thracian city in modern Bulgaria remained on the bottom of the artificial lake. This mistake, from the times of historical and national nihilism, can be corrected today and Seuthopolis can be returned into the treasure house of world cultural heritage.
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The ancient city is taken back from the water through a circular dam wall, resembling a well on the bottom of which, as on a stage, is presented the historical epic of Seuthopolis. 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 – an exceptional possibility for excavations of such a scale. The movement with the panoramic elevators providing access to the ground level further enriches this impression.

Zheko Tilev’s proposal to uncover and preserve Seuthopolis (pdf)