The fourth largest country in Africa, Libya consists of three historical regions, which are Tripolitania, Fezzan and Cyrenaica. Archaeological sites in Libya attract a large number of tourists and the country has many Roman and Greek ruins. Leptis Magna, for instance, was a prominent city of the Carthaginian Empire and Roman Libya, while Cyrene was the oldest and most important of the region’s five Greek cities. Sabratha was the westernmost of the ancient three cities of Roman Tripolis. As-Sahra al-Libiyah, the largest erg of the Sahara, Red Castle Museum, Jebel Akhdar, and Martyrs' Square, Tripoli are some of the top attractions in the country. Flights to Libya from London may be limited due to the closure of some airports and the travel warning issues against travelling to Libya.