Commuters swarmed through London as they walked to work this morning as the Tube strike hit services across the capital.
Members of the Rail, Maritime and Transport union mounted picket lines outside stations after walking out at 9pm last night.
The action will last for 48 hours and will be followed by a three-day stoppage next week.
The two sides are embroiled in a fresh row over the closure plans, which the union warned threaten safety as well as almost 1,000 jobs.
LU denied there would be any impact on safety and said ticket office staff would provide a better service if they were moved to other parts of stations.