In land we gained from the sea (the Flevopolder) a canon was found last week.
The canon is in a very rusty shape and old (16th century). When it'll be restorated, the canon is another example of life before creating a lake from a sea.
In those days when it was the bottom of the sea ships sailed there to go from Amsterdam to Frisia (Friesland), Kampen, Hardewich (Harderwijk).
At the shore near the findingplace of the remains of the ship there were 2 castles and maybe there was warfare too to control the seaway and the trade between the villages, cities of the Republic of the Seven Provinces of the Netherlands.
Update:
cycle stats:
about 26 k
about 1 hr
(counter didn't work)