The ruins of the Roman theater are located on the southern slope of São Jorge Castle, in the parish of Santa Maria Maior, formerly in the extinct parish of Sé, in Lisbon.

The theater was built in the first century, in the time of the Roman emperor Augustus. It was rebuilt in the time of Emperor Nero, and during the reign of Constantine was partially dismantled. Abandoned in the fourth century , it remained buried until 1798, the year the ruins were discovered after the 1755 earthquake.

The object of several archaeological campaigns since 1967, has thus recovered part of the benches, orchestra, stage and stage and a large number of decorative elements. It was under the purview of architect Francisco Xavier Fabri that the first excavations began in order to know the state of the ruins.

Site museum, located in the historical part of the city, this nucleus of the Lisbon Museum aims to reveal what was one of the most important monuments of Olisipo. 

The museum is housed in two buildings from different eras, one from the eighteenth century and the other from the late 19th century. XIX, exemplary of industrial architecture and where it operated a printing shop and a luggage factory. This building was restored and adapted for the installation of the former Roman Theater Museum, inaugurated in late 2001. 

After two years of closure, for new archaeological campaigns, total museum remodeling and improved accessibility and comfort, the Museum of Lisbon - Roman Theater opened to the public on 30 September 2015. 

The Museum of Lisbon - Roman Theater comprises long-term exhibition area and archaeological field.

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