Abstract: A construction jack-up barge comprising a barge (11) supporting a tower (13) in a stowed horizontal position for transport and a vertical position for deployment. The tower (13) has three fold-out legs (15), each equipped with a footing assembly (17). The tower (13) is supported for rotation between a horizontal stowed position and a vertical position for deployment, about the barge (11), by a pivotal connection (19). The tower is also supported in a traveling frame (20) which has concave shaped rollers (21) which track each chord of the tower (13), allowing the tower (13) to be moved up and down relative to the barge (11), when the tower is being deployed. In the vertical position the tower (13) is received through an opening which extends through the deck to the hull of the barge (11). A central cut out portion (33) extends from the stern of the barge (11), to the opening, to provide a pathway for the tower (13) as it rotates between the horizontal and vertical positions.