Hadrian's Library, Athens

While not much remains of this Roman-era library today, it must have been a marvel during its heyday in the 2nd century AD when it enclosed a cloistered court with a hundred columns. Emperor Hadrian, a fervent admirer of Greek culture (earning him the nickname "Graecula" or "Little Greek"), outfitted this expansive complex with art galleries, lecture halls, and a grand central public space. His rule marked an era of peace and prosperity, fostering the flourishing of arts and culture; that left an indelible mark on the Roman Empire.

During Hadrian's time, the library served as a repository for valuable papyrus scrolls and various artworks. It suffered damage during the Herules invasion but was later restored by the Roman leader of Athens, Herculius. Over time, the ruins became the site of three churches: a Byzantine church dating back to the 5th century, a 7th-century church, and a 12th-century cathedral.

The site has only recently become accessible to the public and is still undergoing excavation; however, a few original Corinthian columns have endured, providing a sense of the library's impressive scale. It's particularly striking to realize that the Tetraconch Church, whose remains lie at the center of the site, was constructed entirely within the library's internal courtyard.

Tip:
Admission is included with the Acropolis ticket, so it's certainly worth a visit. Alternatively, you can get a sense of the site by strolling along the fenced perimeter and peering through.