"Older than the centuries; older than the D'Urbervilles!" (58.30)
When Angel realizes that he and Tess have arrived at Stonehenge, he exclaims immediately about how old it is. It's older than the D'Urbervilles, and "older than the centuries." Older than time? Earlier in the novel, the ancient, "primaeval" forest of The Chase near Trantridge, and the May Dance tradition were our previous markers of the really, really ancient. Now, Stonehenge just blows them all away in the absolutely, time-out-of-mind, ancient-beyond-belief category.