Rideau Canal
Also known unofficially as the Rideau Waterway.
Connects Ottawa, Ontario, to Lake Ontario and the Saint Lawrence River at Kingston, Ontario.
202 km long. The canal system uses sections of two rivers, the Rideau and the Cataraqui, as well as several lakes.
The canal was opened in 1832 as a precaution in case of war with the United States. It remains in use today primarily for pleasure boating, with most of its original structures intact, operated by Parks Canada. It is the oldest continuously operated canal system in North America, and in 2007 it was registered as a UNESCO World Heritage Site.
Construction was supervised by Lieutenant-Colonel John By of the Royal Engineers. Private contractors including John Redpath, Thomas McKay, Robert Drummond, Thomas Phillips, Andrew White. Construction started in the autumn 1826, and was completed by the spring of 1832.
There were hundreds of deaths from disease, principally complications from malaria. However, accidents were fairly rare for a project of this magnitude, and inquests were held for each accidental death.
John By was held to account for cost overruns, and was recalled to London and was retired with no accolades or recognition for the tremendous accomplishment for which he bore responsibility. By had repeatedly warned that the pioneering work was underfunded.
The above information is largely condensed from the comprehensive Wikipedia entry.
By's work is commemorated in Ottawa in a variety of ways, including the 'Colonel By day' civic holiday. Ottawa was originally named Bytown. A recent account of By's achievements may be found here[1].