In the title mol-ecule, C(17)H(14)O(4), the C atom of the carboxyl group deviates by 1.221 (3) Å from the plane [maximum deviation = 0.0122(2) Å] of the tricycic ring system. In the crystal structure, inter-molecular O-H⋯O hydrogen bonds link the mol-ecules into centrosymmetric dimers, and π-π inter-actions [centroid-centroid distances = 3.491 (3), 3.591 (3), 3.639 (3) and 3.735 (3) Å] link these dimers into layers parallel to the ac plane. Weak inter-molecular C-H⋯O inter-actions further consolidate the crystal packing.