Mayor Bloomberg and MTA Chairman Jay Walder walked through the 34th Street cavern for the No. 7 subway line extension on Wednesday.
The extension costs $2.1 billion and is the first subway extension in several decades, according to a released statement.
Concrete and railroad tracks have already been put in place. The tunnel boring machines began underneath the 26th Street and mined a combined 2,900 feet to create a tunnel that will extend the No. 7 line to the 11th Avenue and 34th Street.
The line is projected to open in 2013.
