The country with cities named Sofia, Varna, and Plovdiv is Bulgaria. Sofia, the capital, is located in the western part of the country and is known for its rich history and cultural landmarks. Varna lies on the coast of the Black Sea and is famous for its beaches and maritime activities. Plovdiv is one of the oldest cities in Europe, featuring a blend of Roman, Ottoman, and Bulgarian architecture. Bulgaria is known for its diverse landscapes, significant historical sites, and vibrant culture.