The UN "name" mediator, Matthew Nimetz, as well as other ministers from both countries attended the ceremony, as did the European Union enlargement commissioner, Johannes Hahn, the European Union foreign policy chief, Federica Mogherini, as well as the UN's Under-Secretary-General for Political Affairs, Rosemary DiCarlo.
A flare thrown by protesters highlights riot police guarding the parliament during a demonstration against the agreement between Greece and Macedonia over a dispute of the former Yugoslav\'s republic name, in Athens, on Saturday.
Lawmakers backed Tsipras by rejecting the motion brought by the opposition New Democracy party, which had accused him of granting too many concessions to Macedonia in the deal, which is set to be signed Sunday.
"The time has come again to sing happy songs in the Balkans", Tsipras said, moments before the document was signed by the two countries' foreign ministers.
Since Macedonia first declared independence in 1991, the small Balkan country's name has been a point of contention with Greece, which has long argued that the title suggests the nation has a claim on the northern Greek province of the same name.
The Prime Ministers of Greece and FYROM, Alexis Tsipras and Zoran Zaev, are scheduled to meet in a spot on Prespes Lake, a body of water in northern Greece that borders both countries and has been chosen for its symbolism.
"Today you are all mortgaging the future of the country", he told lawmakers.
Both sides say data on their side in Harvard admissions suit
The institution fired back in its own filing, stating the 2013 study was "incomplete, preliminary, and based on limited inputs". Harvard argued that its records initially should be filed confidentially to protect students and the admissions process.
Specifically, by officially recognizing a Macedonian language and nationality, it is nearly certain that the country will be called Macedonia by the broader world, instead of North Macedonia, opponents of the deal argue.
Across the border, Zaev has also met with opposition, with President Gjorge Ivanov saying he will not sign off on the agreement. Zaev has said he will put it to a referendum in the autumn.
"With the signing of the agreement between Macedonia and Greece, everyone will benefit", Zaev said Saturday.
Previously, Athens blocked his country from taking steps to join both the 28-nation bloc and the North Atlantic Treaty Organization, two groups he now hopes will offer invitations to start talks within weeks. "Macedonia and Alexander the Great is Greek history and culture, and they are just giving it away to Skopje." he said.
But the agreement still needs to be approved by both parliaments and by a referendum in Macedonia. The process will take months.
The document, in which Greece agrees to drop its veto over Macedonia's European Union and North Atlantic Treaty Organisation membership, and will be submitted to the parliament in Skopje Tuesday.
Thousands of Greeks protested against the deal outside parliament on the day of the no-confidence motion, calling for the prime minister's resignation. If that passes, Ivanov is required to approve the legislation, which would then be ratified.