The Cannon Blast ceremony (El Cañonazo de las Nueve) is one of the oldest and attractive traditions of Havana. In colonial days, the shots signalled the closing of the gates of the walled city and the rising of the chain across the entrance to the harbour. The tradition of firing a cannon every night at 9:00 pm was kept even after the wall was torn down and is still used for checking your watch.

The neighbors of the town insisted to the town council on the need to create a new public square for their amusement. In 1587, the town council decided to use as a public square the area behind the Convento de San Francisco, which was being built at the time. During the latter decades of the 16th century, this square was called the Plaza Nueva (new square), but from the 18th century onwards, once the Plaza del Cristo had been built, it began to become known as the Plaza Vieja (old square). The most remarkable feature of this square are the buildings around it, with their unquestionable historical and artistic importance of having been the blueprint for a style of architecture which, along with certain developments, subsequently spread throughout the city and characterised the Cuban architecture of the 18th century.

The Cathedral of Havana is an iconic work of what is known as Cuban Baroque and the most remarkable of our colonial churches. The glorious baroque facade and asymmetrical bell-towers of the late 18th-century cathedral are the square’s top attraction. Its interior is surprisingly plain, but it once held the remains­ of Christopher Columbus. Religious services are held here. It has been declared a National Monument.

The vast Fortaleza de San Carlos de la Cabaña, known as ‘La Cabaña’, running beside the harbor, was constructed after the English capture of Havana in 1763. The largest of the military structures built by Spain in the Americas, this fortress was completed in 1774 and its presence formed an effective complete deterrent against the country's enemies. The polygon, occupying an area of around 10 hectares, consists of bastions, ravelins, moats, covered walkways, barracks, squares and stores.  It is impressively well preserved, and the gardens and ramparts are romantically lit in the evening. This fortress hosts the spectacular nightly ceremony of El Cañonazo de las Nueve (cannon fire at 9), the firing of a cannon that marked the closing of the city gates, one of Havana's longest-held and most attractive traditions.