Hope and Arthur's Graves.
Crestwood Cemetery is where Arthur Trent and Hope Cahill are buried and the location of the Clue, Vinegar. It is located in Boston. This cemetery is where the Clue Vinegar is located. Amy and Dan go here in the Black Book of Buried Secrets and find a letter in the compartment the Clue is hidden in.
The gravestone in Crestwood Cemetery that the clue Vinegar is located.