The House of Cedar and Pine exists both in a dream state (located in the Red Forest) and in the real world at 10 Old Pines Road in Binghamton, New York. The house holds special significance to the Army of the 12 Monkeys, as the events that transpire there result in the creation of The Witness.
Timeline in the Real World
Cassie tracks down James Cole to this house. He explains that he had seen the house with a "for sale" sign and decided to buy it to make it his home. Cassie recognizes the house from her visions. They argue about staying in 1959. From Cassie's perspective they are giving up on stopping the plague and defeating the Army of the 12 Monkeys. They soon reconcile and confront their feelings about each other, ultimately making love.
On Christmas 1959, Cassie and Cole exchange gifts. Cassie also reveals to Cole that she is pregnant. Their bliss is soon cut short, as Lillian appears to Cole and tells him he must go back to 1957 and stop the primary from being paradoxed.
Before leaving the house to undo everything that happened since 1957, Cole writes "1957-1959 This was Home" in order to stake a claim on a history he was about to rewrite. These words would re-emerge in a vision seen by Olivia in 2016. While Cole undoes history, as a result of existing outside of time, Cassie remains pregnant.
On December 26, 1959, the day after Cole undid the past two years, Cassie, Cole, and Athan splinter in from 2017. The desperate parents hope to save Athan from the destiny promised to him by the 12 Monkeys. Jones, Hannah, and the other members of the facility, using information from Olivia's vision in 2046, arrive and begin shooting at the house. Athan is wounded in the firefight and accidentally splinters back to 2017. Titan arrives behind the house. The Army of the 12 Monkeys takes everyone into custody and sets the house on fire. After their escape from Titan, Cassie and Cole stand outside watching their home go up in flames. The house collapses just as they splinter away.
Timeline in Visions
Olivia enters the house in a vision of the Red Forest. It is in this version of the house where she communicates with The Witness, who only responds via writing on the wall. The Pallid Man also communicates with The Witness in this way. Railly is given a second dose of the red hallucinogen by Olivia and has another vision of the house; this time she goes inside and sees a figure wearing the Witness's robes and mask; the figure is unmasked, revealing Aaron's scarred face underneath.
After returning from 2016, Cassie's mind is tethered to The Witness. She is locked away in his mind while he controls her body. While trapped inside his mind, Cassie enters the house. Through the window, she sees Titan.
Olivia drinks the red tea and enters the house. She discovers that Cassie, Cole, and Athan are at the house on December 26, 1959. Before leaving, she is confronted by The Witness. The Witness reveals her face. Olivia is shocked to discover that The Witness is herself.