Castillo de la Concepción
Most of what can be seen of the castle today was built by Enrique III in the 14th century, using the remains of nearby Roman ruins. The views from here are astounding, reaching out over the town, harbor, and the Mediterranean. A panoramic lift (€2) on Calle Gisbert (excavated in 1878 to join the center of the city to the sea) rises nearly 150 feet to a gangway that leads to the Concepción Castle. Besides saving a strenuous walk, the gangway also offers great views on the way up.
Refugio Museo de la Guerra Civil
Cartagena suffered through much aerial bombardment during the Spanish Civil War, since it was the base for most of the Republican fleet. For the safety of its citizens, shelters with a capacity of 5,500 were built into the sides of the Concepción Hill. At the musum, visitors today can see the conditions people had to endure during those harrowing days.
Casa de la Fortuna
At the remains of the Casa de la Fortuna, which belonged to a wealthy family of the 1st century BC, the most attractive feature is the fresco painted on the dining-room walls. It's to the south of the tourist office, down the main road.
Barrio del Foro Romano
This interesting Roman forum remained buried for over 20 centuries until excavations in 2008 and 2009 into the hillside revealed an entire block of Roman buildings. Highlights here include a thermal bathing complex, atrium, and the Decumano Calzada Romana, a section of the Roman road that originally joined the harbor and forum. The paintings on the walls of the banqueting hall in the atrium and the mosaics in the baths are of particular note.
Across from the tourist office on the San José hill, the Punic Wall dates from 227 BC. The walls enclosed and helped defend the Punic city that became the capital of the Carthaginians on the Iberian Peninsula.
Discovered in 1987, the Teatro Romano dates from the late 1st century BC. This impressive theater was built into the northern slopes of the Concepción Hill and could seat over 6,000 spectators. The museum displays the most important pieces found during the excavation.
A block from the House of Fortune, the Augusteum remains were once two important public Roman buildings dating from the 1st century BC. It's thought that they were used as a place where the priests of the cult of the Emperor Augustus met to spread the imperial ideology during his reign. There are group visits only during the week, but individuals may visit on weekends, book at the nearby Casa de la Fortuna.
A little distance outside the old town, and built over the 4th-century Roman necropolis of San Antón, the Museo Arqueológico is the headquarters for all archaeological study in this area. Exhibits give you a good idea of Cartagena's history from prehistoric times (there's a large display of fossils) to the Romans whose architecture, weapons, amphoras, and coins dominate the museum.