Old Fortress, Corfu, Greece © Netfalls Remy Musser/Shutterstock
This imposing structure is the Old Fortress on the Greek island of Corfu, off the western coasts of Greece and Albania. Situated in a strategic location between the Ionian and Adriatic seas, Corfu became one of the most fortified places in Europe amid successive sieges by the Ottoman Empire. The island was ruled by the Republic of Venice for 400 years until the late 18th century, which built forts in Corfu"s Old Town to defend its maritime trading interests. They held off three Ottoman sieges in 1537, 1571, and 1716 but have been repaired, rebuilt, and added to over the centuries. The Old Fortress has witnessed the rise and fall of mighty empires for hundreds of years, from the tip of a rocky peninsula jutting into the sea. These days, however, it is home to the public library and Corfu"s archives.