Basilica

Before it named a church, basilica named a Roman civic building, a long rectangular hall used for law courts, markets and public administration, entered along its length and often ending in a semicircular apse where a magistrate sat to hear cases. When Constantine legalized and then patronized Christianity in the early fourth century, this secular hall, rather than any earlier temple form, became the model for large scale Christian building, because its open interior suited congregational assembly in a way a Greco-Roman temple, designed to house a cult statue rather than a crowd, did not.

Constantine's own building program produced the first great Christian basilicas in Rome, including Old St Peter's and San Giovanni in Laterano, both raised directly on the civic basilica plan: a long nave flanked by lower side aisles, a row of columns marking the division, and the apse, once the magistrate's seat, now holding the altar. This plan proved durable precisely because it was structurally simple, requiring no advanced vaulting technology, and it remained the basic template for church building across the Mediterranean world for centuries, long after more elaborate domed and Gothic forms developed alongside it in particular regions and periods.

In current Catholic usage, basilica has split away from its architectural meaning to become a canonical rank the pope grants to a church of particular devotional, historical or artistic importance, entirely independent of whether the building actually follows the ancient basilica floor plan. The Holy See distinguishes a basilica major, a category held today by only four churches, all in Rome, from the far larger number of basilica minor churches distributed worldwide.

A basilica minor might be a modest parish church that happens to house a significant relic or shrine, granted the title in recognition of its pilgrimage importance rather than its architecture, and it receives specific liturgical privileges along with the designation, including the right to display a distinctive umbrella-like canopy called the ombrellino and a bell called the tintinnabulum in processions. This administrative sense of the word coexists, sometimes confusingly, with its purely descriptive architectural sense: a building can be a basilica in floor plan without holding basilica status, and a building can hold basilica status while following an entirely different plan, whether Gothic, Baroque or modern. The title, in effect, marks significance rather than shape.