The Roman Catholic Basilica is devoted to Our Lady of Good Health. The Devotion to Lady of Good Health of Velankanni can be traced to the mid-16th century and is attributed to three miracles at different sites around where the Bacilica stands at present. The three miracles include: The spirit of Mary and the Christ Child to a slumbering shepherd boy, curing of a lame buttermilk vendor and the rescue of Portuguese sailors from a violent sea storm.

However it was the promise of the Portuguese sailors that was the immediate cause of a permanent edifice being built at Velankanni. The chapel was dedicated on the feast of the Nativity of the Blessed Virgin Mary. The nine-day festival and celebration is still observed and draws several pilgrims each year. The Shrine of Our Lady of Velankanni, also known as the "Lourdes of the East,"[2] is one of the most frequently visited religious sites in India

The shrine became a parish church in 1771 when Catholics in India were under persecution from the Dutch. Later in the year 1962 it was granted a Special status of a Minor Basilica by Pope John XXIII.

Architecture of Basilica
Layout of the Basilica complex: Basilica, Nadu Thittu shrine-site of second apparition, Adoration & Reconciliation chapel, Our Lady`s Pond-site of first apparition, Stations of the cross, Stations of the Rosary, Stations of the Sacraments. The Basilica has been built in Gothic style. In 1928 the southern side was extended and northern in 1933. The Shrine Basilica contains three chapels, Our Lady`s Tank, Church Museum, Priests` Residence, Offering Center, Stations of the Cross, Stations of the Rosary, Shrine Mega Mahal and Vailankanni Beach.

The church of Immaculate Heart of Mary (managed by the Jesuits) was demolished and the statues were brought to the Shrine of Our Lady of Good Health. In 1933 the Shrine expanded with two new wings, to the right and to the left of the `Main Altar`, meeting the nave at right angles.

A spacious vestry was provided immediately behind the Altar. The entire sacred edifice began to assume the shape of a Latin cross. In the centre of the ancient main altar is the miraculous image of Our Lady of Good Health.

In 1956, a new arch was blessed and opened by Bishop Sundaram. In January 1961, a new central altar, made of white marble, was erected replacing the former one made of cement concrete.

In 1974-75, an extension of the basilica was built behind the existing central altar in order to accommodate the multilingual pilgrims. The extension included a two storied church, high dome and high gothic spirals. The extension resembles the Basilica in Lourdes, France.

Basilica as a Pilgrimage centre
Pilgrimage is common during September, around the time of the feast. The feast day prayers are recited in Tamil, Malayalam, Telugu, Kannada, Konkani, Hindi and English languages. The pilgrims include people with different faiths. She is called Shantadurga as per Goan and konkan coast Hindus. It is believed that the portrayal of Virgin Mary as a curer of illness and a victor over all demonic forces is seen by local Hindus as an attribute equivalent of Hindu Goddess Mariamman.