The party will trudge trough the valley initially, but ultimately what happens is up to you guys. At the start, it will be rough terrain, desolate, barren and eery. Century old gravestones will be littering the ground, the narrow cobblestone ways are already in a bad shape of disrepair with deep holes, missing pavement and tricky roots springing up. There are swamplands, there will also be crypts, burial chambers deep in the cliffs and more, but i don't want to spoil things. Ultimately, it will be 40% outdoors to 60% indoors the way i see it, but the party might do something different entirely so...