A 500-tonne crane is being used to remove 20 Tube carriages from the Waterloo and City line so they can be refurbished.
The trains are being lifted by crane and transferred for refurbishment
The line has been closed for five months so Tube maintenance firm Metronet can replace all of the track on the one-and-a-half mile route.
A number of roads will stay shut around Waterloo station, in south London, during the weekend for the removal.
The trains have not left the tunnels for 13 years.
A spokesman for Metronet said: "The trains are like pit ponies as they haven't left the tunnels since 1993.
"This five month closure is the first opportunity we have had to take the trains out and fully refurbish them."
The operation began at about 0600 BST on Saturday and is expected to last all weekend.
Seven low-loaders are being used to take the carriages to a depot in Doncaster for refurbishment.
The Waterloo and City line is London Underground's shortest route with only two stops, Waterloo and Bank.
It carries a relatively small average of 37,000 commuters a day, and is 107-years-old.
The line is not open at weekends.
Despite some opposition from commuters, Metronet said the closure would benefit them in the long run with five trains able to work at peak times instead of the current four.