Crisis after crisis: Europe's 2015 rollercoaster ride
"I have no doubt that this is the most critical moment in our history," declared European Council President Donald Tusk, about half-way through this tumultuous year.
He was talking about the imminent threat of Greece falling out of the eurozone - a crisis that has faded from the headlines, yet remains in many ways unresolved.
But he could have been referring to the entire year - a white-knuckle rollercoaster for the European Union, that has seen the notion of European solidarity tested to the limit, and some of the EU's most cherished achievements called into question.
Crisis has been followed by crisis.
From the struggles of the eurozone, high unemployment and political disenchantment, to the conflict in Ukraine and relations with Russia.
From a million refugees and migrants arriving on European shores, and borders closing, to home-grown terrorism and the failure of cross-border co-operation between police and intelligence services.
And, looming large next year, there is the very real prospect that, in the middle of all of this, one of Europe's most powerful countries, the UK, could vote to leave the EU altogether.
In or out?
So, where next?
The European Union has often taken its boldest steps at moments of crisis. But although the political impulse to "keep the show on the road" remains strong, 2015 feels a little different.
Even among those countries that have integrated most closely, a number of competing visions of Europe have emerged during the year.
A broadly north-south split on how to strengthen the eurozone has been mirrored by a broadly east-west split on how to begin to cope with a million arriving migrants.
Dominating debate and dividing opinion - on these and other issues - is a Germany that seems to have put its historical baggage behind it, and is now Europe's clear leader.
Berlin appears determined to build a stronger EU, often in its own image, but it will not have everything its own way. Keep an eye on growing opposition to German leadership in 2016.
Proposals from the European Commission focus on more integration: creating the post of a eurozone finance minister, for example, or an EU border guard force, with the power to intervene against the wishes of an individual member state.
Big problems do need big solutions. But finding detailed agreement in 28 different capitals, on such far-reaching issues of national sovereignty, is proving extremely difficult.
The days of 15 or even six original member states are long gone. The EU is much more complicated now.
One obvious weakness is structural. That is partly because the EU is an experiment in shared sovereignty, which has never quite been tried before.
The clear-cut solution to many of its problems would be to go the whole hog, and create something approaching a federal state. Or to transfer many powers back to nation states that still co-operate, but have far fewer institutional links.
But the current dispensation - muddling along in the middle - is perhaps the most difficult of all to get right.
In part, the EU has only itself to blame. Two of its most prominent creations - the euro and the Schengen passport-free zone - are incomplete constructions.
In both cases, the big ideas were put into practice without all the building blocks properly in place.
And when they have come under unexpected pressure, systems created in the spirit of compromise have proven to be barely fit for purpose.
It has all led to an atmosphere of gathering gloom, some of it unwarranted.
For all its problems, Europe is still one of the most attractive places in the world to live. Why else would a million people have risked everything to get there?
But the relative decline of Europe as a global power has generated anxiety, as high unemployment and low growth in many countries have sapped confidence in existing political structures.
Anti-establishment parties of the radical left and right have made gains throughout the year.
In January Syriza took power in Greece, and in December Podemos helped break the two-party stranglehold in Spain, by criticising what both leftist parties see as failed austerity policies.
On the right, the National Front (FN) in France and UK Independence Party in the UK won millions of votes by campaigning against both the EU and national immigration policies.
An all-too-cosy political consensus has fractured.
As 2016 approaches though, this may not be a time for mulling over long-term trends. It is all set to be another year with short-term crisis management to the fore.
And if there is one thing the EU needs above all else, it is clear political leadership, to help Europe navigate through the storms to come.