It is one of the main churches of the Catholic Church in Malta and a landmark of Valletta. It was built by the Knights of Malta from 1573 to 1578 and acquired the same status as the Archdish Church of Mdina at the beginning of the 19th century. From the outside, its khaki-coloured walls are not conspicuous, but the interior is heavily decorated with gorgeous Baroque styles, including staggered carved stone walls depicting the vaults and side altars of St. John's life scene. It is one of the most beautiful churches in Europe.