A pipe-laying vessel including a pipe-laying tower extending upwardly from the vessel, said tower comprising: - a first lower section extending upwardly from a proximal end to a distal end above the main deck of the vessel, and - a second upper section movably mounted on the first lower section, and said tower being arranged to have a first pipe-laying configuration for laying pipeline in which said second upper section is positioned above said first lower section and pipe is passed from said second upper section to said first lower section when, in use, it is being laid, and being arranged to have a second stowed configuration in which said second upper section is moved relative to the said first lower section and the overall height of the tower is reduced, wherein a first end of said second upper section is pivotally connected to the distal end of said first lower section to enable the tower to be converted between the first pipe-laying configuration and the second stowed configuration, and said second upper section is pivotable in relation to said first lower section such that a second end of said second upper section can pivot down to be supported on a deck of the vessel when in the second stowed configuration, wherein the pipe-laying vessel also comprises a pipestring elevator for rotating a pipestring from a substantially horizontal orientation at the base of the tower to an orientation substantially parallel to the tower and wherein said pipestring elevator is arranged to be mountable for movement along the tower such that the pipestring elevator can rotate the pipestring to be substantially parallel to the tower and then lift the pipestring up the tower, and wherein said pipestring elevator is arranged in the form of a strongback such that in the rotation stage, said pipestring elevator is simultaneously translated towards the tower whilst a first end of said pipestring elevator nearest to the tower is lifted up the tower and wherein said pipestring elevator is further arranged to be mountable at its first end such that as said first end is moved up the tower from the base of the tower to a height up the tower corresponding to the length of the pipestring, the pipestring is rotated to be substantially parallel to the tower and then when said first end is moved further up the tower, the pipestring is lifted up the tower, and wherein said first end of said pipestring elevator is mountable on a winch system such that said first end can be pulled up the tower. - a first lower section extending upwardly from a proximal end to a distal end above the main deck of the vessel, and - a second upper section movably mounted on the first lower section, and said tower being arranged to have a first pipe-laying configuration for laying pipeline in which said second upper section is positioned above said first lower section and pipe is passed from said second upper section to said first lower section when, in use, it is being laid, and being arranged to have a second stowed configuration in which said second upper section is moved relative to the said first lower section and the overall height of the tower is reduced, wherein a first end of said second upper section is pivotally connected to the distal end of said first lower section to enable the tower to be converted between the first pipe-laying configuration and the second stowed configuration, and said second upper section is pivotable in relation to said first lower section such that a second end of said second upper section can pivot down to be supported on a deck of the vessel when in the second stowed configuration, wherein the pipe-laying vessel also comprises a pipestring elevator for rotating a pipestring from a substantially horizontal orientation at the base of the tower to an orientation substantially parallel to the tower and wherein said pipestring elevator is arranged to be mountable for movement along the tower such that the pipestring elevator can rotate the pipestring to be substantially parallel to the tower and then lift the pipestring up the tower, and wherein said pipestring elevator is arranged in the form of a strongback such that in the rotation stage, said pipestring elevator is simultaneously translated towards the tower whilst a first end of said pipestring elevator nearest to the tower is lifted up the tower and wherein said pipestring elevator is further arranged to be mountable at its first end such that as said first end is moved up the tower from the base of the tower to a height up the tower corresponding to the length of the pipestring, the pipestring is rotated to be substantially parallel to the tower and then when said first end is moved further up the tower, the pipestring is lifted up the tower, and wherein said first end of said pipestring elevator is mountable on a winch system such that said first end can be pulled up the tower.