St Peter's was built between 1857 and 1859, originally as a new Catholic parish church for Lancaster. Catholics had been given freedom to build churches 30 years earlier in the Catholic Emancipation Act of 1829. The new church replaced a small chapel in nearby Dalton Square.
In 1924 Pope Pius XI created the Diocese of Lancaster, and St Peter's was chosen to be the Cathedral church.
In 2009 the Cathedral will celebrate its 150th anniversary. A much fuller account of its history is given on the
150 section of the Cathedral website.