The centre of the town, with its mediaeval atmosphere, preserves the remains of the ancient walls of the original Christian village, created in the late 13th century. Visitors can wander through the narrow streets laid out in an orthogonal pattern that were once surrounded by walls. One of the three entrances to the mediaeval village, called Portal de Sala, still stands as the only surviving entrance. Within the old town's layout, one can also admire sections of the old walls integrated into the houses, such as those in the courtyard of La Casa de la Cultura, at the corner of Carrer Sant Lluís with Carrer Mestre Blasco, and at the toy store called La Muralla.

In the old nucleus of the town, some of the most representative architectural buildings of the Pegolí heritage can be found. The sightseeing tour can be started at the Church known as Església de L’Assumpció, which dates back to the late 16th century. Within the church, visitors can marvel at wonderful works of art, such as the Gothic altarpiece by Antoni Peris dedicated to La Mare de Déu de L’Esperança (the Virgin of Hope), the double Veronica icon attributed to Jacomart, the 16th-century Christ carving by Damià Forment, and the paintings on the main altar by Rafael Cardells, among many other treasures. The tour could continue with a visit to the chapel of Ecce-Homo (1759), located on the site of the former hospital for the poor. The chapel is the work of Francisco Cabezas and is said to be a precursor to his major work, San Francisco El Grande in Madrid. It stands out for its daring architecture, featuring an octagonal dome adorned with blue tiles.

In the historic centre, next to El Portal de Sala, La Casa de Cultura building can be seen. This cultural centre is housed in a restored 18th-century ancestral building that once belonged to the wealthy Sala family. Lastly, there is the Town Hall of Pego, located in a noble building constructed in 1857. It stands out for its arched colonnades with a corridor that leads to the little square known as Placeta dels Porxins.