GERMANY: In 2017, when archaeologists initially unearthed the foundations of a large 2nd-century A.D. Roman building buried near Cologne’s center, they believed it was a public assembly hall. However, further excavations revealed that the interior walls were lined with a series of peculiar niches, uncharacteristic of such a structure. Experts now believe that these recesses were once used to store scrolls, as many as 20,000, and that the ruins are those of Germany’s earliest known public library.