Greek Prime Minister Costas Karamanlis has accepted an invitation to visit Turkey, underlining closer ties.
Relations between the two countries have markedly improved of late
It will be the first official visit by a serving Greek head of government for more than 40 years.
It was confirmed as Mr Karamanlis and Turkish PM Recep Tayyip Erdogan met at the common border to launch the construction of a joint gas pipeline.
The project is designed to transport Caspian and Central Asian natural gas to Europe and be operational next year.
The pipeline will stretch for 300km (186 miles) between the two countries, most of it on Turkish soil.
The project is estimated to cost less than $18m.
Both leaders stressed its historic significance.
It is symbolic of what both countries see as an end to years of deep mutual distrust, says the BBC's Jonny Dymond in Istanbul.
Less than 10 years ago, the two countries came close to war.
Each nation was born under the occupation of the other. Forced population exchanges between the two left a legacy of bitterness, our correspondent says.
There are still disputes over air space and territorial waters.
Many in Greece would also like to see the Orthodox Church, which is based in Istanbul, freed from some of the restrictions of the Turkish state.
But last year, Mr Erdogan paid an official visit to Athens for the first time in 16 years.
The last Greek prime minister to visit Turkey in an official capacity was Constantinos Karamanlis, the uncle of the present premier, in 1959, reports the AFP news agency.