(the port gate). Both ports were eventually abandoned due to silting. Several popes attempted to improve navigation on the Tiber in the 17th and 18th centuries, with extensive dredging continuing into the 19th century. Trade was boosted for a while, but by the 20th century, silting had resulted in the river only being navigable as far as Rome. The Tiber was once known for its floods — the Campus Martius is a flood plain and would regularly flood to a depth of . There were also numerous major floods; for example, on September 15, 1557 the river flooded to a height of 62 feet above sea level and over 1,000 people died. The river is now confined between high stone embankments, which were begun in 1876. Within the city, the riverbanks are lined by boulevards known as lungoteveri, streets "along the Tiber". Because the river is identified with Rome, the terms "swimming the Tiber" or "crossing the Tiber" have come to be the shorthand term for converting to Roman Catholicism. A Catholic who converts to Protestantism, in particular Anglicanism, is referred to as "swimming the Thames" or "crossing the Thames". In ancient Rome, executed criminals were thrown into the Tiber. People executed at the Gemonian stairs were thrown in the Tiber during the later part of the reign of the emperor Tiberius. This practice continued over the centuries. For example, the corpse of Pope Formosus was thrown into the Tiber after the infamous Cadaver Synod held in 897. Bridges In addition to the numerous modern bridges over the Tiber in Rome, there remain a few ancient bridges (now mostly pedestrian-only) that have survived in part (e.g., the Ponte Milvio and the Ponte Sant'Angelo), or in whole (Pons Fabricius). In addition to bridges, the Metro trains use tunnels. Representations Following the standard Roman depiction of rivers as powerfully built reclining male gods, the Tiber, also interpreted as a god named Tiberinus, is shown with streams of water flowing from his hair and beard. 2022 Heatwave In 2022, there was a major heatwave in Europe. The water levels dropped and a number of objects emerged. Some of these objects include World War 2 shipwrecks, bombs and a 2000 year old bridge. See also Hollywood on the Tiber References External links Rivers of Italy Rivers of the Apennines Drainage basins of the Tyrrhenian Sea Waterways of Italy Rivers of Emilia-Romagna Rivers of Lazio