A seawall is basically a coastal defense to prevent waves and tsunamis. Let's suppose there is a town that is located in a lagoon next to the ocean, a sea version of Esgaroth, the lake town.
In this town, with a 16th century technology, is it possible to build a seawall with length of 5 kilometers in the ocean delta, like this?
This town basically encounters heavy storms more than thrice a year, and big waves (about 5 to 10 meters) hit the town. This causes hundreds to die and causes serious damage to the town. (This town earns money with trading.) But this town harbors more than tens of thousands, so hundreds might not have a serious impact. Also, the town will be located inside the seawall.
I did some research about seawalls and their materials, but it looks like a seawall made out of pebbles and stones might not be a good building material for this. Concrete would be a best solution, and I am not very sure whether 16th century technology can create tons of concrete and cement.
So the conditions are:
- Must use solid materials
- 5 kilometers of seawall
- Has to be stable enough to last a couple hundred years
- Maximum construction time: 30 years
Would it be possible to build a seawall with 16th century technology in these conditions? (Assume the town can provide infinite money and workers.)