The tower room was where Joshua Collins placed his son Barnabas' coffin when he discovered Barnabas had become a vampire (447) while he searched for a cure. Joshua summoned the white witch Bathia Mapes to Collinwood (449) to do battle against Angelique for Barnabas' soul in the tower room. She failed horribly and died at the Old House, being completely consumed by fire (451).
Nathan Forbes discovered Barnabas's hiding place and, in a moment of spite, told Naomi Collins her son was still alive and locked up in the tower (456). Naomi climbed the stairs to the tower room and found Barnabas there, showing signs of vampirism. She became despondent, drank sherry laced with arsenic, and then went up to the tower room, where she died in her son's arms (458).
After this, the tower room was sealed off and unused until 1896 or 1897, when Jenny Collins went insane and was kept there for her own protection, so that her husband would not know she was still alive, and to prevent a family scandal. Beth Chavez went to the tower three times a day to feed Jenny (707). Jenny escaped with the assistance of Rachel Drummond (716), who saw the lights in the tower several times after being told no one had been there in over 100 years, since some great tragedy had occurred there (707-711).
From the inside, the tower room is shown as having stained glass in the windows, but only plain windows from the outside (448).