L L.
Yelp
14thC church, ruined in the 1755 earthquake. This site was founded as a museum in 1864.
The museum consists of the ruined church structure, which is outdoors in that there is no roof, so you are exposed to the elements. At the far end of it, where the chancel would be for architecture of the era, is an enclosed museum. The indoor portion houses various artifacts, some Roman epigraphy, some tribal items brought by Portuguese explorers from the Meso- and South Americas, and some prehistoric items from the excavation of Castro de Vila Nova de S. Pedro, dating to the Neolithic (Stone Age) and Chalcolithic (Copper Age) periods.
There is a gift shop at one end of the indoor portion, which carries a number of books on archaeology. The gift shop has a beautiful window looking out over the city, with visibility straight to Castelo de S. Jorge. This museum also serves as the headquarters of the Association of Portuguese Archaeologists.
Tickets are 4€, or 5,50€ for a guided tour. If you have the Lisboa card, it's only 3,20€, and it's free for kids under 14. They offer discounts for seniors, students, and disabled persons.
Having been to big archaeological exhibits at the National Gallery in London, the Met in NYC, and the University of Pennsylvania Museum of Archaeology at home in Philadelphia, the collections at Museu Arqueológico do Carmo were not as vast or varied, but they held my interest just the same, and their context inside ruins that (as another Yelper mentioned) are older than my country, made me think a lot about how cultures study one another, and view one another as museum collections, representative of entire peoples who live and breathe as you and I, just in a different time and place. I think the exhibits really accomplished showing me this relativity in a way that other archaeological exhibitions have not. The volume of artifacts at the abovementioned museums, just seem too large to comprehend in the way I could this much more digestible number of pieces, juxtaposed in small rooms side-by-side, bringing such vastly different cultures into close vicinity. For me, it was a great historical / anthropological perspective.