After Voldemort killed his father and paternal grandparents, they were buried in the graveyard by the church in Little Hangleton (GF1). This, then, is also where Harry was taken by Portkey, saw Cedric Diggory killed and Voldemort reborn, and duelled Voldemort in 1995 (GF34).
Commentary
Notes
An early publicity photo of Harry in the Little Hangleton graveyard showed some clear errors on the tombstone of the Riddles: 
The stone shows that Tom Marvolo Riddle is buried there, but that would be Voldemort. Fans spoke up loud and clear, pointing out the error. By the time the film was released, the tombstone had been "fixed":
Either way, the tombstone indicates that the murders of the Riddle family happened in 1943. However, this does not agree with canon, which says that the murders happened in Voldemort's sixteenth year, which would be 1942.
From the Web
Story from Beyond Hogwarts about the tombstone error: http://www.beyondhogwarts.com/story.200509262.html