Medieval performers across all of Europe were generally itinerant travellers with a wagon to use as a stage wherever they could find an audience. Plays were still based on the stories that audiences would be familiar with, namely the stories of the Christian church. Morality plays would entertain whilst at the same time informing the illiterate masses of their moral obligations to the church and state.
Triptych: The Crucifixion (1443/1445) by Rogier van der WeydenKunsthistorisches Museum Wien
In Britain, these plays were later adopted by the craft guilds and presented as part of the religious festivals such as Easter. The carpenters would tell the story of The Crucifixion, the fishmongers would perform Jonah and the Whale, and so on.
Cities such as York, Lincoln, Coventry and Chester had their own cycles of guild plays performed every few years under the auspices of local authorities, the texts of which survive and have often been adapted into modern performances by both professionals and amateurs.
The Passion Play performed every ten years in Oberammergau, Germany is probably the closest a modern audience can get to the experience but that in itself was a much later revival of the old tradition.
Proscenium Arch of a Court Theater (18th century) by Anonymous, Italian, 18th centuryThe Metropolitan Museum of Art