Definitely! If you're staying all three days in Helsinki there's the Design District Helsinki - Designkortteli,the Suomenlinna fortress, Helsinki Cathedral. Temppeliaukion kirkkois also a quite distinct church. If you're into museums the Kiasma and the Designmuseo are my top recommendations. I'd recommend going for a typical Finnish sauna experience. Also, if you're willing to travel outside Helsinki, Porvoois the most charming little town and it's pretty close by. Enjoy Finland!
Mentioned in this answer:
Debbie
Luc
Camille