EU leaders and top officials will celebrate the 60th anniversary of the signing of the Treaty of Rome in Italy on Saturday 25 March.
The document, signed by West Germany, Belgium, France, Italy, Luxembourg and Netherlands in 1957, laid the foundation for the economic and political bloc.
EU Council President Donald Tusk, EU Commission President Jean Claude Juncker and EU Parliament President Antonio Tajani will be taking part in the celebrations over the weekend as around 5,000 police secure Rome just days after the Westminster terror attack in London.
"Our parents and grandparents founded this Union with one common vision: never again war. It was their strong conviction that breaking down barriers, working together – and not against each other – makes us all stronger. History has proven them right," Juncker said.
"For 60 years, the values on which this Union is built have not changed: Peace, freedom, tolerance, solidarity and the rule of law bind and unite us. They must not be taken for granted and we must fight for them every day.
"Our democracy, our diversity and our independent and free press are the pillars of Europe's strength – no individual or institution is above the law. The European Union has changed our lives for the better.
"We must ensure it continues to do so for those that will follow us. For now, all roads lead to Rome. After Rome and however it is paved, there is only one way forward: European unity."
But UK Prime Minister Theresa May will not be taking part in the events and Foreign Secretary Boris Johnson will be attending a high-level trade forum in Turkey. May has promised to trigger Article 50 of the Lisbon Treaty on Wednesday 29 March and trigger two-year-long divorce talks with the EU.
An anti-Brexit demonstration organised by United for Europe is planned in London on Saturday.The campaigners have contingency plans for up to 50,000 people attending the protest, IBTimes UK has learned.