The day also coincided with the Feast of the Immaculate Conception.
AFP reports the mass was followed by the opening of the gates leading to the pilgrim trail which thousands are expected to walk during the coming year, to the site where Bernadette Soubirous lived and experienced 18 apparitions of the Virgin Mary between February and July 1858.
These include the church in which she was baptised, the former prison cell where her poverty-stricken family lived, and the grotto where she had her visions and a chapel.
Bishop of Lourdes Jacques Perrier said while there had been no new building to mark the 150th anniversary, unlike the basilica constructed at the time of the centenary, five coloured mosaics of gospel scene would be unveiled on the grey church.
The pope is expected to visit Lourdes at some point during the celebrations, Perrier said.
Last week, the Vatican said plenary indulgences would be granted for a limited time to pilgrims who visit Lourdes for the 150th anniversary.
In Rome, the Pope marked the feast of the Immaculate Conception by praying at a statue of Mary and prayed for the Lourdes pilgrims.
"I ask the Virgin Mary to watch over the inhabitants of Lourdes and I grant all of them, as well as the pilgrims attending the ceremonies, an affectionate apostolic blessing," Pope Benedict said.
Catholics mark 150th anniversary of Lourdes apparitions (AFP, 09/12/07)
LINKS (not necessarily endorsed by Church Resources)
St Bernadette pilgrimages
St Bernadette (Wikipedia)
Plenary indulgence (Wikipedia)
Special plenary indulgence for Lourdes pilgrims (CathNews 06/12/07)
Pope to make Lourdes pilgrimage (CathNews 14/11/07)
Priest offers $5000 to disprove miracles of Lourdes (CathNews 30/08/04)
Italian woman healed at Lourdes (CathNews 15/11/05)
Church probes new Lourdes cure (CathNews 09/09/03)
Stronger Pope thanks God for Lourdes pilgrimage (CathNews 19/08/04)
10 Dec 2007