An assembly for realising a lamp incorporated into a masonry wall, comprises a lamp housing that delimits a lamp seat suitable to house a lamp body, and a mould suitable to be removably fixed to the lamp housing and to the inner side of a formwork in which the pouring is carried out, so as to realise, after pouring cement in the formwork, a light-emission cavity open on the outer surface of the masonry wall. The mould is suitable to rigidly support the lamp housing before and during the pouring of the cement and is provided with mould fastening means suitable to removably fix the mould to the inner side of the formwork.