for every year
A poem or story for every year since 1400.
(It is in honour of the year, it doesn't need to be set then.)
So: Fort Assumption was built in 1753, so that explains that. Sunflowers were introduced to Europe in 1510, so that explains that. And so on.
The project works chronologically.
That's it.
OK.
Nice.
because
a thing for every year