The Roivas Mansion is located on the Roivas Estate in Rhode Island, USA. It contains the Tome of Eternal Darkness, which Alex finds in a small study. In addition to being the location of several chapters, it serves as a hub where the player controls Alex in between chapters. However, when the player enters the ruins of Ehn'gha, they cannot return to the mansion.
The mansion was built when Rhode Island was still a British colony. It is not known when exactly it was built, but it appears to have been lived in for quite some time when Maximillian Roivas inherits it in 1760 AD. Prior to that date, it was the home of Aaron Roivas, Maximillian's father. Aaron discovered that the mansion was built directly over the cavern containing the ruins of Ehn'gha, and it is unknown if the Roivas' responsible for the construction of the mansion chose the site deliberately knowing this.
Throughout Edward's chapter, the servants mention that the mansion is unable to be kept clean for long, and even expressed doubts that the mansion could ever be maintained. Whether this was due to the Ancients' influence or not is never stated.
Servants were present in Max and Edward's chapters, although with notable differences: In Max's chapter, most of the servants were bonethieves in disguise and thus enemies (many of them acting friendly until Max gets the Tome of Eternal Darkness), while in Edward's chapter, they were allies (exempting if they were fed on by the Vampire, in which case they become zombies and thus enemies). No servants exist in Alex's chapter (not counting the hung servant during one of her sanity effects).
The main foyer is located on the first floor, with a pair of stairs leading up to the second floor. A coffee table with a telephone is located in the vicinity, which in Alex's chapter causes a sanity effect where Edward seemingly calls her from the grave and utters the same statement he said at the end of her dream in the beginning. On the second floor portion there is a painting of a pristine paradise (though in Maximillian's Chapter, when losing sanity, it instead changes to a painting depicting a hellish landscape). In the final chapter, a unknown individual (presumably Michael Edwards, though this is unconfirmed) rings the doorbell from outside and then hastily places a package inside before hurriedly leaving that contained the third Ancient Essence (which one varies on which ancient Pious chose in the playthrough) and, should he have gotten it in the prior chapter, the Enchanted Gladius.
The bathroom is located on the second floor, it contains a lavatory, a bathtub and a sink. Upon examining the bathtub, Alex will experience a sanity effect of seeing herself dead in a bath of blood.
The servants quarters is located on the second floor, being the second door on the right in the hallway leading up to a stained-glass window. Alex Roivas is the only one of the Roivas family who actually visits the room during her playable scenario, as Edward's scenario has the room covered up in wallpaper (although he can hear a scream when passing by the area the door was at), and although the room technically exists in Max's chapter, Max himself cannot actually enter it during the chapter as it is locked, although he notes a forboding element in the room (foreshadowing his later murder of the servants within under the suspicion that they were bonethieves). Alex Roivas accessed the room via a pick axe left behind by her grandfather, shortly after discovering the cause of his demise, also discovering a stethoscope and a set of three bodies and one of them missing a skull. Note that accessing this room acts as a turning point for the story, as after this, Alex Roivas will encounter various monsters under the control of the antagonistic Ancient (which one depends on the playthrough) in the mansion.
The library is located on the first floor in the East Wing, and contains a family tree depicting a hung man on it, several books depicting the various histories of the Roivas family, as well as various subjects including sociology, psychology, and various medicinal sciences. A grandfather clock also exists in the room, although it actually acted as a lock for a secret passageway leading to the study where the Tome of Eternal Darkness was located, and can be accessed by moving the clock hands to the thirty-third minute of the third hour. The Library was not accessible during Maximillian Roivas' chapter, although it as well as the secret passage to the Eternal Darkness' holding place may have been constructed by him during the three months between his discovery of Ehn'gha and his being thrown into an insane asylum, as he knew and told Edward Roivas (himself having just arrived at the mansion) how to access the room to "complete his work" when appearing before him as a ghost. A maid also fell victim to the Vampire shortly after Edward Roivas acquired the Tome of Eternal Darkness, with Alex Roivas at one point encountering her ghost who is complaining in terror that she "can't get the blood out." In addition, Alex Roivas also occasionally manages to find flying books in the room as she is losing her sanity. She also manages to find the Heart of Mantorok behind one of Lindsey's pulp novels.
The Kitchen is located on the first floor, where meals were prepared at the mansion. Originally, it was separate from the Dining Room, although they merged by the time of the 1950s and 2000. Maximillian Roivas located a Pump Handle in one of the pantries inside the kitchen. In addition, when conversing with one of the maids, she casually commented to Max that there was a strange quality hanging in the air, causing him to become suspicious (note, when conversing with her, the music will change to the general "Eternal Darkness" overworld theme).
Dining Room/Piano room
The Dining/Piano room is located on the first floor, just beyond the stairs on the west wing of the mansion. During Maximillian Roivas' chapter, it contained a dining table as well as a fireplace that was actually a secret passageway to the room where the tome of Eternal Darkness was kept, which could only be accessed by moving the Raven statue to the antagonistic Ancient's hated enemy (which one depends on the Ancient the player chose in The Chosen One). By the 1950s, the room was redone entirely, having a piano inside, which Edward Roivas intended to get practice in, but ultimately didn't before he died. Alex also has a sanity effect in this room, where after playing the piano, she notices a servant being hung by a noose swaying gently in the room. When she investigates the corpse, the dead man's eyes suddenly open up and he vanishes, with a disembodied, inhuman voice being uttered stating that "the darkness is coming."
- The Roivas Mansion is given an indirect reference in Super Smash Bros. Ultimate when fighting the Zero Suit Samus puppet fighter for Alexandra Roivas, as the battleground used is Luigi's Mansion from the game of the same name. Coincidentally, both Eternal Darkness and Luigi's Mansion deal with the player traversing through a haunted mansion to solve mysterious circumstances regarding the death/disappearance of the protagonist's relative (Mario in Luigi's case, and Edward Roivas in Alex's case).