Opening the entrance to the Order's underground tavern in Phantom Blade Zero took me longer than I'd like to admit, but it's required to continue progressing through Pangzhen during the Town of Death quest.
In the wine yard behind the tavern building, Soul will note that the pavilion's floor on the right is hollow—this is where the secret entrance is, so you'll want to head behind the pavilion and smash the big black jar, as in the video above.
This reveals a crank which will unlock the cellar and let you inside. Similar to Weeping Creek Valley's outpost or the Crimson Forest's Thieves Camp, this is an important location in Pangzhen and a hub for many of the region's sidequests.
English (US)