Abstract: A platform (2) in an interior platform for a tubular tower such as a windmill tower (24) made from steel is disclosed—and more specifically, a platform (2) adapted to be assembled in situ from construction element members in order to fit the inside wall (22) of the tower (24), comprising a basic, preferably circular, center module (4), radial, telescoping supporting beam members (6), wherein the construction element members are modules (10, 12 and 14) which are independent of the diameter of the platform (2), and two-piece pivotable modules (16) which incline for mounting as a periphery ring next to the inside wall (22) of the tower (24).