The Poisoner's Tower
 
The Poisoner keeps to himself and is a hard man to find. Few know that the studious sage in the tower outside of town is the old assassin and that the plants he grows are almost all poisonous, venomous, or both.

Most people coming to visit the tower do so seeking the sage’s advice – officially usually political or botanical, but often looking for access to the assassin’s guild or to acquire poisons and antitoxins.

The structure contains large window boxes for growing poisonous plants, some lab space to work on the poisoner’s craft, and the usual things you’d expect to find in an odd home (bedroom, study, secret basement with even secreter basement with a nice sturdy locking closet for keeping people against their will, or for locking yourself into to pretend to be someone needing rescue, etc.)

You can grab the map for your personal or commercial use from the post at https://rpgcharacters.wordpress.com/2017/10/13/the-poisoners-tower/