The biggest church in Rome after St Peter’s (and the world’s third-largest) stands on the site where St Paul was buried after being decapitated in AD 67. Built by Constantine in the 4th century, it was largely destroyed by fire in 1823 and much of what you see today is a 19th-century reconstruction. However, some treasures survived the fire, including the 5th-century triumphal arch, with its heavily restored mosaics, and the gothic marble tabernacle over the high altar. This was designed in about 1285 by Arnolfo di Cambio together with another artist, possibly Pietro Cavallini. To the right of the altar, the elaborate Romanesque paschal candlestick was fashioned by Nicolò di Angelo and Pietro Vassalletto in the 12th century and features a grim cast of animal-headed creatures. St Paul’s tomb is in the nearby confessio. Looking upwards, doom-mongers should check out the papal portraits beneath the nave windows. Every pope since St Peter is represented and legend has it that when there is no room for the next portrait, the world will fall. There are eight places left. The stunning 13th-century Cosmati mosaic work in the cloisters (admission free; 9am-1pm & 3-6pm) of the adjacent Benedictine abbey also survived the 1823 fire. The octagonal and spiral columns supporting the elaborate arcade are arranged in pairs and inlaid with beautiful colourful mosaics.