Basilica of St. Pius X (Lower Basilica)

The Basilica of Saint Pius X, usually known as the Underground Basilica, is one of the largest churches in the world and one of the most unusual. It lies beneath the esplanade of the Sanctuary of Our Lady of Lourdes, in the south-west of France, and it was built for one purpose: to shelter huge crowds of pilgrims who came to the shrine. The Marian apparitions to the young Bernadette Soubirous took place at the Grotto of Massabielle in 1858, and by the twentieth century the older churches could not hold the numbers who came for ceremonies, particularly in bad weather.

The basilica was built in the 1950s for the centenary of the apparitions and was consecrated on 25 March 1958 by Cardinal Angelo Roncalli, who became Pope John XXIII a few months later. It was designed by a team of architects led by Pierre Vago, with the engineer Eugène Freyssinet advising on the structure, and the engineering was a feat of its day. The plan is an oval about 200 metres long and 80 metres wide, covering about 12,000 square metres, and the building can hold around 25,000 people. The shape is built entirely of reinforced concrete, with huge beams that span the space with no interior columns in the central area.

Inside, the atmosphere is plain and quiet. The concrete walls are left largely bare, and the decoration is limited to panels and paintings of saints and blessed figures, together with decorative elements of coloured glass that catch the light. The size and the lack of ornament give a sense of a great hall designed for communal prayer, and it is used for the large international Masses, the Eucharistic celebrations and the evening ceremonies, which are especially moving when the space is full. Services are held in many languages.

Visitors should remember that this is a working place of worship and keep silence during services. The basilica is open daily for most of the day, with hours that change between the summer and winter seasons, so check the sanctuary's website. Admission is free, as in the rest of the sanctuary. Allow thirty minutes to an hour.

The basilica suits pilgrims, those interested in modern religious architecture and engineering, and travellers visiting Lourdes who want to see the sanctuary beyond the grotto. It sits close to the Basilica of the Immaculate Conception, the Place du Rosaire and the Grotto of Massabielle, and walks along the Gave de Pau river lead away from the crowds.