Where did alberto and sophie meet to talk about the middle ages?

They meet at a nearby church.

In "Sophie's World" by Jostein Gaarder, Alberto and Sophie meet at Sophie's cabin in the woods to discuss the topic of the Middle Ages. The cabin becomes a space where Alberto continues to educate Sophie about the history of philosophy and various philosophical ideas. In this particular instance, they explore the intellectual developments and philosophical thoughts that emerged during the Middle Ages, a crucial period in the history of Western thought.