Rachel never owned an apartment. For the first 5 seasons, she lives with Monica, then she moves in with Phoebe. When she has to move out because of the fire, she moves in with Joey. When she gets pregnant and Ross feels left out, she moves in with Ross. After the birth of Emma, she moves out because of a fight and lives with Joey for the rest of the show. After the series finale, she presumably moves back in with Ross.