An ancient port, it thrived under Roman, Byzantine and Norman rule and even rivaled Venice. It was bombed heavily during World War II and not many historical buildings have survived.

The Basilica of St. Nicholas is a beautiful example of Romanesque architecture. The story of the arrival of the saint's relics in Bari goes back to the 11th Century when three ships stopped at Myra where the saint's shrine had been an important pilgrimage site, and using the pretext that the important relics were threatened by the Ottomans, the crew broke the shrine open and took the relics away, making a narrow escape from the pursuit of the outraged townspeople. There was a great celebration as the relics arrived in Bari, and a majestic church was erected to house them. The relics were placed beneath an altar in the crypt by Pope Urban II. Pilgrims flocked to Bari as it became known that the tomb continued to exude manna just as it had in Myra. The manna is extracted every year during the festival on May 9 that celebrates the translation of the relics to Bari. The manna is diluted and sold in hand-painted bottles with images of the saint. According to the believers, this liquid can bring healing and produce miracles. During the annual festival, the priests take an icon of St. Nicholas to a boat to spend the day at sea. Upon the icon's return, a procession escorts it back to the basilica. The next day, Eucharist is celebrated in the open and a colourful statue of St. Nicholas is paraded through the streets. The festival culminates in a service during which the manna is extracted on the third day.

Austere from the outside, the basilica's interior includes fine depictions of the saint's life and miracles, and a silver altar in the right transept. The floor mosaic dates back to the 12th Century. In 1966, an Orthodox chapel was built by the crypt for Orthodox liturgy. Orthodox guests are invited to the service on May 9, and the basilica contains Orthodox statues and icons. This reflects the attitude of the Dominican brothers that St. Nicholas is all Christians' saint, whatever their expression.