Latest government figures show a steep rise in the number of suspected sham weddings reported by registrars in England and Wales, many as a result of organised gangs helping illegal immigrants to stay in Britain.
It should be the most romantic day a couple can enjoy.
Surrounded by family and friends, it's the chance for two people to tell the world they love each other. A big party, a few tears and then the happy-ever-after.
That is the way it is supposed to be, but a very different kind of marriage is on the rise - the sham marriage.
Every year in the UK hundreds of weddings take place between people who barely know each other - brides and grooms who have never met before and may never meet again.
It is a way for desperate people to try to get around immigration controls. Marry someone with an EU passport and you get to stay. It is illegal but plenty try.
Panorama has been investigating this worrying trend and sent me undercover into this secretive world.
Posing as a reporter for a made-up television station called Marry Me, I turned up at Brent register office in north London. With my shiny suit and cheap buttonhole, I looked worryingly convincing.
We were here for the wedding of Ghazanfar Ali and Maria. He was a 29-year-old from Pakistan, she was Spanish and 46. Our tip off was the marriage was dodgy.
I arrived before the bride and groom and - in my role as Marry Me correspondent - chatted to the wedding party.
The bride 'Maria' was marrying Ghazanfar Ali using a stolen identity
There wasn't a lot of romance in the air.
"Tell us about the bride," I said to one guest, still wearing his London Underground uniform.
"I don't know her. I was at work and he just rang me and said 'it's my wedding today'."
Then the happy couple turn up. She looks much younger than her mid-40s and is asked to prove who she is.
Fortuitously she has turned up with a pile of utility bills that prove her address. The registrar has her doubts, but has to marry them.
"Looking at the couple and the interaction between them, it looked pretty suspicious," the registrar told me.
All she could do was recommend the Home Office should investigate.
But I wanted to know more about our happy couple, so we started our own investigation.
We found Ali first. He was living in East London in a house full of men, from the steady traffic in and out of the door. Maria was nowhere in sight.
Ali ran a fast food restaurant. When we sent a researcher to talk to him, he asked her out on a date. This was just a week after his marriage.
"I live alone, no girlfriend - everyone needs a relationship", he told our researcher.
In the eyes of the law however, he has a brand new bride.
FIND OUT MORE
Richard Bilton reports Panorama: My Big Fat Fake Wedding
BBC One, Thursday, 24 March
Maria was harder to find. Her name is not registered anywhere in this country, but we found her in Majorca.
I caught up with her as she was getting back from a shopping trip and was surprised to discover she was not the same Maria as the one that married Ali.
It turns out this woman had been a victim of identity fraud.
Her passport was stolen when she was working in London last year. It was used in the marriage application.
When I told her that in the UK she was now officially married, she burst into tears.
"How could they do this to me?" said the real Maria. The truth is, quite easily.
During our investigation, we found solicitors who were more than happy to take money to process illegal applications and pimps who - for a few thousand pounds - would rent out a prostitute with paperwork to meet and marry a groom of your choice.
Sham marriages have trebled in the last three years and the situation is predicted to get worse.
Currently, a foreign national has to apply for a Certificate of Approval (CoA) from the Home Office to get married.
If someone does not have a right to be in the UK, they are denied approval.
233,000 marriages were registered in England and Wales in 2008
CoAs have not stopped illegal marriages but have provided a barrier. From next month, the certificates are to be scrapped.
The Law Lords said they were an infringement of human rights as they discriminated between civil marriages and Church of England marriages which did not require the certificate.
The government has chosen not to replace them.
"What will replace them is effective enforcement," the Home Office Minister Damian Green told me.
"That's the way to make it clear to the criminal gang behind the sham marriages that they will get caught. And we've in the last few months arrested 155 of them," Green continued.
Many registrars don't share his enthusiasm and fear a steep rise in the number of sham marriages.
"I can't describe how frustrating that is in terms of the system of marriage being abused, the system of our immigration laws being abused," said Mark Rimmer, Superintendent Registrar for Brent.
When I went to knock on Ali's door, his flatmate said he had moved out and had not been seen for a few weeks.
Maria has reported the identity theft to the Spanish Police - but they say it's a UK matter.
The marriage still stands. There are few happy endings in the world of sham weddings.
Panorama: My Big Fat Fake Wedding, BBC One, Thursday, 24 March at 2100 GMT and then available in the UK on the BBC iPlayer.
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