Turkish invasions, making Corfu one of the few places in Greece never to be conquered by the Ottomans. Palaio Frourio The old citadel (in Greek Palaio Frourio (Παλαιό Φρούριο) is an old Venetian fortress built on an artificial islet with fortifications surrounding its entire perimeter, although some sections, particularly on the east side, are slowly being eroded and falling into the sea. Nonetheless, the interior has been restored and is in use for cultural events, such as concerts (συναυλίες) and Sound and Light Productions (Ηχος και Φως), when historical events are recreated using sound and light special effects. These events take place amidst the ancient fortifications, with the Ionian sea in the background. The central high point of the citadel rises like a giant natural obelisk complete with a military observation post at the top, with a giant cross at its apex; at the foot of the observatory lies St. George's church, in a classical style punctuated by six Doric columns, as opposed to the Byzantine architectural style of the greater part of Greek Orthodox churches. Neo Frourio The new citadel or Neo Frourio (Νέο Φρούριο, "New Fortress") is a huge complex of fortifications built by the British during their rule of the island (1815–63) dominating the northeastern part of the city. The huge walls of the fortress loom over the landscape as one travels from Neo Limani (Νέο Λιμάνι, "New Port") to the city, taking the road that passes through the fishmarket (ψαραγορά). The new citadel was until recently a restricted area due to the presence of a naval garrison, but old restrictions have been lifted and it is now open to the public, with tours possible through the maze of medieval corridors and fortifications. The winged Lion of St Mark, the symbol of Venice, can be seen at regular intervals adorning the fortifications. Angelokastro Angelokastro ( (Castle of Angelos or Castle of the Angel); ) is a Byzantine castle on the island of Corfu, Greece. It is located at the top of the highest peak of the island's shoreline in the northwest coast near Palaiokastritsa and built on particularly precipitous and rocky terrain. It stands on a steep cliff above the sea and surveys the City of Corfu and the mountains of mainland Greece to the southeast and a wide area of Corfu toward the northeast and northwest. Angelokastro is one of the most important fortified complexes of