The pueblo of grass roofed buildings, round river-stone plazas and pre-Colombian magic is off limits to camera-clad foreigners.

BBC: Colombia��s spiritual centre

"Whether it is a high water level or low, the Merced River flows year round and the current can pull anybody in, " said Gediman.

CNN: STORY HIGHLIGHTS

In 1807, Robert Fulton's "North River Steam Boat" (popularly known as the "Clermont") began chugging its way up New York's Hudson River on its successful round-trip to Albany.

CNN: Saturday,