Charlie visits the Warren state home for the first time toward the end of the novel, out of curiosity. He wants to see what the facility looks like and how the residents are treated. He meets the people who run the facility, sees the other intellectually disabled people who live there and how they occupy their time, and understands the degree to which the residents are free or imprisoned.
Charlie does all this because he's recently found out that his advanced intelligence is expected to deteriorate rapidly, and that the Warren home will be his own home when he becomes unable to take care of himself in the real world. At the facility, Charlie decides that the director and staff members seem like decent people with good intentions, but he's disturbed that there's no talk at all about hope for the residents' improvement. It's a place where people go to spend their lives closed off from society, waiting to die, he concludes.
As the novel comes to a close, Charlie again goes to the Warren home: this time as a resident. He's ready to head there, he explains, because he doesn't want people in the real world feeling sorry for him, and because he wants to be among people like himself.