I saw tear gas and Tsipras at Athens' final massive rally for a NO vote in the Greek referendum

ATHENS, Greece — The ‘No’ campaign against a bailout deal had its last and biggest rally here on Friday night, ahead of the referendum on Sunday which could decide Greece’s economic and political future.

The crowd started building early, ahead of Prime Minister Alexis Tsipras’ speech.

There was a huge social and age mix in the crowd — though there were dozens of left-wing groups in attendance, it’s nothing like a political rally I’ve seen in the UK since the Iraq War demonstrations.

Tens of thousands of people turned up to Athens’ Syntagma Square.

Take a look at how it looked from down on the ground.

The referendum has been like a minor stimulus programme for anyone selling Greek flags.

Hours ahead of the start of the rally, and even longer before Tsipras' speech, demonstrators started putting up their placards.

Some people made their own signs.

Even before 7 p.m. (for a rally that started at 7:30), the crowd had started to fill up the bottom half of the square.

When I arrived on Sunday there were basically no campaign materials for the referendum -- they have sprung up everywhere since.

That includes this particularly memorable photo of German finance minister, Wolfgang Schaeuble who is not a popular figure in Greece.

The Yes campaign argues that the referendum is effectively about the euro -- with a No vote meaning a return to the drachma.

The No campaign disagrees, but there are supporters that seem happier to leave the currency union if necessary.

The Yes campaign was holding a rally nearby, in front of the old Olympic stadium.

Though it's hard to say who will win, the difference between a Yes and No vote could eventually mean Greece staying in or leaving the eurozone.

At the No rallies, there are usually dozens of left-wing groups in attendance, with their own banners.

There was a big divide in terms of age at the event, from the very young to the very old.

And there were speakers from all over Europe too, including statements from Spain's radical Podemos party, and Ireland's Sinn Fein.

There was one small bit of violence -- the group with red flags here, just away from the demonstration, clashed with the police on a road off Syntagma.

It was brief and very small in comparison to the size of the protest, but it showed that the police are constantly waiting in the wings here, just in case.

The air was stinging with the tear gas used -- you can see the residue here on the ground.

The violence was an extremely limited part of the protest -- the vast majority was good-natured, just as every other demonstration I've been to since being in Athens.

The polls right now in the referendum are too close to call, showing either Yes or No just a couple of percentage points ahead of each other.

But a close vote could be a problem, feeding into the already tense political situation.

I wasn't sure what this sign meant, but the man who owned it was quite insistent that I get a picture.

Some of the Yes and No posters have been a little boring, but this one was great -- a real work of art (though I didn't know what the bricks said).

One huge banner came from the United Popular Front, one of Greece's many anti-austerity movements.

The crowd filled up on all sides well before Prime Minister Alexis Tsipras was due to appear at 9 p.m.

Here are some more people at the Oxi / No protest.

Syriza MP and speaker in the Greek parliament, Zoi Konstantopoulou, swept through behind Prime Minister Alexis Tsipras, who was too quick for a photo.

Moments later finance minister Yanis Varoufakis, who looks taller on TV, followed on from behind, pushing towards the stage.

Panayiotis Lafazanis, energy minister and hard-left firebrand, who has hinted that a plan B for life outside the euro was being constructed.

The crowd was bursting with energy from the moment Tsipras pushed through, and all the way through his speech.

Of course, he's playing to his crowd that supported him in the first place -- but they love him. One woman asked me if I'd noticed how much better looking he is than former PM Antonis Samaras.

Current polls suggest that Sunday's vote could be extremely tight -- neither Yes nor No seems to have a clear, solid lead.

Now see:

Shipping container cranes line the Pireaus cargo port on February 11, 2015 in Pireaus, Greece.

Photos of Greece's colossal shipping port show you why the economy is in tatters

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