Theater of Dionysus
Although an attack on the city in 86 BC had damaged the theater, restoration was carried out and a speakers’s platform was added in the 2nd or 3rd century CE. It was then decorated with marble depictions of myths by the archon Phaidros in the 5th century CE.
After being buried by earth fill, the theater was finally excavated in 1838 by the Archaeological Society of Athens, with work continuing into the 1880s. Further excavations and restorations started to be carried out again in the 1980’s and continue today.
Sources:
https://www.ancient.eu/Greek_Architecture/
https://www.ancient.eu/article/814/theatre-of-dionysos-eleuthereus/