London Mayor Sadiq Khan says he is "surprised" it has taken so long to introduce an all-night London Underground service, with the first trains set to run on Friday night (August 19).
The Night Tube finally begins this weekend, and a specially-recorded audio message spoken by the Mayor will be played in carriages.
Trains will operate through the night on the Victoria line and parts of the Central line, with the Jubilee, Northern and Piccadilly lines following in the autumn.
Speaking about the long-delayed launch, Mr Khan couldn't resist having a pop at his predecessor Boris Johnson , after disputes with the rail unions meant the services are coming in almost a year later than planned.
Mr Johnson, now Foreign Secretary, was criticised for announcing the September 12 2015 start date before these disputes were resolved.
Mr Khan accused Mr Johnson of "giving up" on the all-night Tube before leaving City Hall in May.
He said: "It's not me making a cheap point, but the previous Mayor did announce the Night Tube start date on one occasion and that wasn't met, on a second occasion, that wasn't met, on a third occasion, that wasn't met, and then gave up.
"My point is TfL staff work incredibly hard. It can't be beyond the wit of a full-time mayor and TfL to make this work properly.
"When I see the enthusiasm from employers in London, investors to London, tourists in London, about the Night Tube, it's surprising it's taken us this long to get it.
"I'm pleased and proud that we're here."
The Mayor said he had ensured the introduction of all-night services was "meticulously" planned, with just two lines being opened initially because "we don't want a big bang (with) errors and mistakes".
He added: "There may well be teething problems when we first begin but the key thing is to learn from that and to improve upon that before we unveil the other lines later on this year."
Asked who would use the Night Tube, Mr Khan said passengers would include nurses, security guards, tourists and even "a middle-aged clubber like me coming home after a late night out with your missus".
He has recorded welcome messages which will be played over the public address system at Oxford Circus, which will be the busiest Night Tube station.
Around 100 British Transport Police (BTP) officers will be on patrol across the network on Friday and Saturday nights.
Superintendent Chris Horton, the officer responsible for policing the Underground, has insisted passengers will be as safe on the overnight trains as they would be during the day .
London Underground (LU) estimates that 200,000 people will use the Night Tube each weekend once it has been opened on all five lines.
About half a million passengers currently use the Tube after 10pm on Fridays and Saturdays combined.
LU's new managing director, Mark Wild, who launched night services in Melbourne, Australia, earlier this year, said: "What happened there is what I expect will happen here.
"It's not just for revellers. It's for the night-time economy - people working in hospitality, shift workers, nurses.
"We expect a nice mix of people who enjoy the fantastic night life of the city, but it's also a lot about giving people mobility."
A recent study by business membership organisation London First estimated the Night Tube could be worth £77 million each year to the capital's economy by 2029.