By Maria Tsangari
The cornerstone was laid in the first unit of the Turkish nuclear power plant in Akugu, in Erdogan's most ambitious project.
Putin and Erdogan watched the ceremony via video conference.
The project was undertaken by the Russian company Rosatom, which is expected to own 51% of the shares.
49% was to be given to a consortium of Turkish companies, but two companies recently withdrew, stressing that they did not agree to the terms of the trade.
Reuters sources say that the sale of shares will probably be postponed for 2019.
Voices of protest are loud inside Turkey, with authorities preventing members of the Anti-Nuclear Platform from entering the region.
Concern in Cyprus as well, as the nuclear power plant will be located at a distance of 48 nautical miles from Kyrenia.
This is one of the most important Turkey-Russia collaborations with the project costing $ 20 billion.
It will include four units, which will produce energy of one thousand two hundred megawatts each.
When fully operational, the plant will generate 10% of the electricity needed by Turkey, or as much energy as Istanbul needs.
Its operation is expected to begin in 2023.