Visit the medieval part of Turku at Aboa Vetus museum. The city had a big fire in 1827, but its medieval stone cellars and paths can still be seen, cause these were buried under the ground when a garden was built. The oldest parts dating back to end of 14th century.
The information is easy to read (Finnish, English, Swedish). Kids have a play area after each stand. There is a modern cafe place in the museum house. I did not have time to go to the art museum, though.
child’s shoe 1300 
medieval house 
horse jaw, horses would heat the house 
streets were covered with wood 
medieval houses like these in Tallinn too 
the stairs lead to an alley behind the house 
modern museum house near the river 
at some time a spa house, sometimes a tobacco factory above the cellars 
museum easy to grasp 
wells were in cellars 
imagine goats jumping on those grass roofs, same in Rauma 
gabbage, turnips and herbs 
old keys 1200-1600
Museum website Abo Vetus
Rauma private guide / Rauman opas 