At the harbour, Isaac Peral's prototype of the submarine, the forerunner of our modern models, and the Wall of Charles III, dating from the 18th century. Leaving the harbour behind us, the Town Hall, a Modernist building dating from 1907, leads us to Calle Mayor, lined with Modernist buildings such as the Casa Cervantes, Casa Llagostera, the Casino and the Grand Hotel in Calle del Aire. Cartagena, Port of Cultures, presents numerous archaeological remains: everyday Roman dwellings such as La Casa de la Fortuna ("The House of Fortune"), with its restored wall frescoes; civic constructions such as the Roman Road and the Thermal Baths at the Decumano and religious buildings such as the Augusteum, raised as a place of worship for the cult to the Emperor Augustus; the Visitor Centre at the Punic Wall (third century BC), the only Punic defence structure that has been discovered in Spain; the 13th century Castle of La Concepción, whose Torre del Homenaje ("Homage Tower") houses the Town History Visitor Centre, featuring easy access via a lift-walkway. However, the most important sight of all is the Roman Theatre, an architectural jewel dating from the first century BC, which, alongside the remains of the Old Cathedral, forms part of a unique visitor centre together with the Theatre Museum. The Spanish Civil War Shelter-Museum is quite unique, offering visitors a fascinating insight into this historical period. Various panoramic views of the town can be enjoyed from the Tourist Bus, whilst the Tourist Boat also provides visitors with an opportunity to discover Cartagena's lively harbour. Municipal Archaeological Museums, National Maritime Archaeology Museum, the Naval Museum and the museum devoted to Carmen Conde. The town's military heritage deserves special mention, encompassing various sections of wall and various castles, as well as the batteries along the coast, located on the hills around the bay and in the surrounding areas.