in Architecture, a kind of gallery on the ground; or a piazza encompassed with arches supported by columns, where people walk under cover. The roof is usually vaulted, sometimes flat. The ancients called it lacunar. Though the word portico be derived from porta, "gate, door," yet it is applied to any disposition of columns which form a gallery, without any immediate relation to doors or gates. The most celebrated porticoes of antiquity were, those of Solomon's temple, which formed the atrium or court, and encompassed the sanctuary; that of Athens, built for the people to divert themselves in, and wherein the philosophers held their disputes and conversations, (see PORCH); and that of Pompey at Rome, raised merely for magnificence, consisting of several rows of columns supporting a platform of vast extent; a draught whereof, Serlio gives us in his antique buildings. Among the modern porticoes, the most celebrated is the piazza of St Peter of the Vatican.—That of Covent-Garden, London, the work of Inigo Jones, is also much admired.