on 9 august 1991, the museum that was established was integrated into the administration of the "instituto português de museus" ("portuguese institute of museums"), under decree 278/91 (diário da república, série-1a). by the end of the 20th century, there was further work completed in the interior on the staircases, vertical accesses and washrooms, along with remodelling of the galleries on the first floor occupied by the secretariat and administration of the museum, as well as the warehouse in 1993. this culminating in the third-phase expansion of the spaces between 1994 and 1999.