Sugarloaf Mountain and Urca Hill Natural Monument Mountain, then an island, on 1 March 1565. The site was chosen to guard the entrance to Guanabara Bay, and the mountain was important as a signalling point. A landfill connected the island to the mainland in 1697, and various buildings were erected to defend the territory, but the Urca urban neighborhood was only built 300 years after the city was founded. The Sugarloaf Mountain and Urca Hill Natural Monument was created by the city of Rio de Janeiro by municipal decree 26578 of 1 June 2006. The objectives are to guarantee green spaces for leisure in a natural area,
Sugarloaf Mound the same civilization that built the mounds at Cahokia. Sugarloaf Mound is on the National Register of Historic Places. The mound got its name in the 18th century when St. Louisans noticed the shape resembled the loaves that sugar was transported in. Although the mound has not been excavated, it is assumed that the mound was used for burials. Sugarloaf Mound measures approximately in height, north/south and east/west. The mound overlooks the Mississippi River, where Interstate 55 meets South Broadway. It is now located entirely within the incorporated City of St. Louis, but used to be on the border between