A crane-support apparatus for mounting a tower crane onto a side of a high-rise building under construction, enabling ascending of the tower crane according to the upwards progression of the building construction, the crane-support apparatus comprising: a chassis configured to support a climbing frame of the tower crane mast; and at least one reinforcement element (110A, 110B, 110C), wherein a distal end of said chassis is hingedly attached to a distal end of said reinforcement element (110A, 110B, 110C), wherein said crane-support apparatus is operational in a deployed, support mode, in which said chassis is aligned in a horizontal position, and is removably attachable at its proximal end to a first predetermined location of said building, such that said chassis is configured to support the climbing frame of the tower crane mast, and in which said reinforcement element (110A, 110B, 110C) is aligned in a slanted position and is removably attachable at its proximal end to a second predetermined location of said building, such that said reinforcement element (110A, 110B, 110C) is configured to provide reinforcement to said chassis, thereby allowing securing of said tower crane mast to said building in said support mode, characterized by the crane-support apparatus further comprising: at least one lifting cable for pulling said chassis and said reinforcement element (110A, 110B, 110C), wherein said crane-support apparatus is operational in a folded, mobilization mode, in which said chassis and said reinforcement element (110A, 110B, 110C) are configured to be pulled by said lifting cable at the distal end of said chassis and the distal end of said reinforcement element (110A, 110B, 110C) with said chassis and said reinforcement element (110A, 110B, 110C) are hingedly folded and aligned in vertical positions when said chassis and said reinforcement element (110A, 110B, 110C) are unattached from said building, thereby allowing displacement, by said lifting cable, of said chassis and said reinforcement element (110A, 110B, 110C) when so folded in said mobilization mode. a chassis configured to support a climbing frame of the tower crane mast; and at least one reinforcement element (110A, 110B, 110C), wherein a distal end of said chassis is hingedly attached to a distal end of said reinforcement element (110A, 110B, 110C), wherein said crane-support apparatus is operational in a deployed, support mode, in which said chassis is aligned in a horizontal position, and is removably attachable at its proximal end to a first predetermined location of said building, such that said chassis is configured to support the climbing frame of the tower crane mast, and in which said reinforcement element (110A, 110B, 110C) is aligned in a slanted position and is removably attachable at its proximal end to a second predetermined location of said building, such that said reinforcement element (110A, 110B, 110C) is configured to provide reinforcement to said chassis, thereby allowing securing of said tower crane mast to said building in said support mode, at least one lifting cable for pulling said chassis and said reinforcement element (110A, 110B, 110C), wherein said crane-support apparatus is operational in a folded, mobilization mode, in which said chassis and said reinforcement element (110A, 110B, 110C) are configured to be pulled by said lifting cable at the distal end of said chassis and the distal end of said reinforcement element (110A, 110B, 110C) with said chassis and said reinforcement element (110A, 110B, 110C) are hingedly folded and aligned in vertical positions when said chassis and said reinforcement element (110A, 110B, 110C) are unattached from said building, thereby allowing displacement, by said lifting cable, of said chassis and said reinforcement element (110A, 110B, 110C) when so folded in said mobilization mode.