Abstract: A modular structure for building parking lots, which is particularly suitable for building temporary parking lots, in which structure each basic modular unit comprises: a rectangular or square composite floor slab (3), four edge beams (4) along the sides of the said slab, four node elements (5) at the corners of the slab (3) for supporting the edge beams (4), four vertical pillars (6) below the said node elements (5), for bases (7) for supporting the structure on the ground below the said vertical pillars (6), a number of ties (8) and/or struts for bracing the structure, the bases (7) comprising means for adjusting the length of the pillars (6) and means for adjusting the position of the base plate with respect to the vertical position of the pillars (6).