Where is it?

Taavetti fortress situated at the important crossroads of Lappeenranta-Hamina and Vyborg-Mikeli highways.

If you are poor alien without car and credit card the best way for you will be the bus from Lappeenranta. Tickets & timetables are here: www.matkahuolto.info. You can try a hitchhike of course. I've tried and did not like it. A waiting was too long. I would walk that distance by the foot more fast...

Apropos:

Grandma on the scooter
in Taavetti city.

Bicycle or scooter would not a bad idea. There are pretty roads for cyclists in every direction.