Alba Iulia is a city in Alba County, Transylvania, Romania. The city is situated on the Mureș River and is famous for its historical and cultural heritage. It has been inhabited since ancient times, and was a significant Roman settlement. In the Middle Ages, it was an important center of Transylvanian Romanian culture and religion.

The city is best known for its impressive Alba Carolina Fortress, which is considered one of the most significant historical monuments in Romania. The fortress was built in the early 18th century and is one of the largest and best-preserved Vauban-style fortresses in Europe. It played a crucial role in the history of Transylvania and Romania, serving as a military stronghold, royal palace, and center of administration.

In addition to the fortress, Alba Iulia is home to several other historical and cultural landmarks, including the Roman Catholic Cathedral of Saint Michael, the Orthodox Cathedral of the Reunification, the Batthyaneum Library, and the National Museum of Unification.

Alba Iulia is also a popular destination for visitors interested in outdoor activities. The city is surrounded by beautiful natural scenery and is located near the Apuseni Mountains. The area offers a wide range of outdoor activities, including hiking, mountain biking, skiing, and caving.