Were they building sites for fortresses? Maybe you were just ahead of the trend! Better go back in another 500 years and check.
Ahaha good call! Will check back later and see ;)
If it's the main lappeenranta fortress you mean I remember being only slightly whelmed by it on a previous visit. So much so that I didn't even get around to having a wandering on Sunday night even though I was staying just across the road