Where Is This?

[Gravdigr]

Originally Posted by ZenGum

To keep the land from falling into the canal, silly.

It ain't working.

Another persistent problem was due to the heavily faulted nature of the sedimentary rock, in an active seismic zone, through which the canal is cut. The canal's high limestone walls have been persistently unstable from the start. Although it was formally opened in July 1893 it was not opened to navigation until the following November, due to landslips. It was soon found that the wake from ships passing through the canal undermined the walls, causing further landslips. This required further expense in building retaining walls along the water's edge for somewhat more than half of the length of the canal, utilising some 165,000 cubic metres of masonry. Between 1893 and 1940, it was closed for a total of four years for maintenance and to stabilise the walls. In 1923 alone, 41,000 cubic metres of material fell into the canal, which took two years to clear out.

That Wiki article (in the link above) is really interesting. For example: It's was in the planning stages since the 7th century B.C.