From left: Joseph Muscat, Malta’s prime minister, and Donald Tusk, president of the European Union, talk as Italian Prime Minister Paolo Gentiloni greets Spanish Prime Minister Mariano Rajoy during a summit marking the 60th anniversary of the signing of the Treaty of Rome, in Rome on Saturday. (Jasper Juinen/Bloomberg News)

There will certainly be fanfare, but also a fair amount of concern, as the leaders of the 27 post-Brexit European Union countries gather in Rome to celebrate 60 years since the signing of the Treaty of Rome, which established the European Economic Community and out of which the present European Union has evolved.

The work that led to the Treaty of Rome was undoubtedly driven by a strong vision of peace and and unity between the nations and peoples of Europe. But today these visions have faded, partly because they are taken for granted, and the E.U. is driven forward far more by the necessity of nations to seek common solutions in more complicated times.

Still the achievements are certainly substantial. War between France and Germany is now so out of the question that raising the issue sounds bizarre, but for preceding generations it was certainly very different. Memories of authoritarian regimes in Southern Europe have faded. The vast enlargement with 10 countries and 100 million people after the collapse of the Soviet empire went remarkably well overall. And the single market has created the largest unified economic bloc in the world and the premier trading entity of the global economy.

Recent challenges have been mastered. Nineteen member states use the euro currency, which enjoys broad public support. All of the E.U. economies are now growing. E.U. growth today is stronger than that of the U.S. economy.

Not bad, particularly considering the starting point. So the prosecco that is likely to flow in Rome is certainly justified.

But the future is still to be written, and the challenges are certainly numerous. The chatter is more likely to focus on these outside the halls where the celebratory speeches are given.

The acute refugee crisis might be over, but illegal migrants from Africa and Asia are still streaming across the Mediterranean from the chaos of Libya. Securing the external borders of the E.U. is easier said than done.

While a decade or so ago there was talk of creating a “ring of friends” around the E.U., today its neighborhood more resembles a “ring of fire.” Ten thousand people have lost their lives in the fighting following Russia’s aggression against Ukraine, and a political resolution looks remote. The Balkans are coming back as a source of concern, with the present standoff in Macedonia a potentially very dangerous one. Relations with strategically important Turkey have deteriorated with a dangerous rapidity. And no one can predict a speedy and stable resolution to the chaos in the Levant.

Then, of course, the United States has gone off on its own uncertain trajectory under the Trump administration. Active verbal hostility to the E.U. from the White House might have given way to cold tolerance, but certainly there is no meeting of the minds across the Atlantic of the sort that has been in the West’s DNA for generations. Indeed, a Pew Research Center poll indicates that European thought leaders trust Trump even less than they trust Russian President Vladimir Putin. We have never been in such a situation before.

The recent Netherlands election might be added to the signs that there is an anti-Brexit and anti-Trump increase in support for the E.U. across Europe, although key elections in France, Germany and Italy are still ahead of us.

The divorce negotiations with Britain could well become acrimonious when the talk turns to money, but there is still hope that it will be possible to shape a new partnership in the years ahead. I believe we will end up with a free trade agreement roughly similar to the one with Ukraine — a vast improvement for Ukraine, but a significant step down for Britain.

Fears of a further breakup of the E.U., which surfaced after Britain’s vote last June, have largely subsided. In fact, there now seems to be more reason to be concerned over a breakup of Britain in the years to come than over a possible further breakup of the E.U. There are many dimensions to the Scottish and Irish issues.

Leading up to the anniversary, the European Commission produced a paper with five scenarios to stimulate the debate on which direction the new EU-27 should take. And more food for thought will be produced in the months to come.

The existing treaties of Europe call for  four meetings of the heads of state and governments of the E.U. countries every year. But last year saw 12 of these meetings, and I count six in the calendar for the first half of this year. There is a clear need to come together and seek solutions to challenges common to all.

It is, of course, highly regrettable that Britain will leave the table around which the leaders of Europe will continue to try to chart a response to the diverse challenges of the future. All stand to lose. The visions of 60 years ago might have faded somewhat, but the necessities in a more complex and contested age will certainly continue to drive the E.U. forward. There will be, the one way or the other, further celebrations in the years ahead.