It is the joy of doing things together that keeps couples happy. In the case of actor Johnny Depp and his fiancee Amber Heard, it seems to be book shopping!

The duo was in town for pre-production work on "Black Mass", a film about the infamous Boston gangster Whitey Bulger. During their trip, the pair headed to the historic Brattle book shop Wednesday, reports contactmusic.com.

"They were very nice. They stayed for a little more than an hour. Probably if we weren't closing, they would have stayed longer," said Ken Gloss, the shop's proprietor.

`He bought a number of books. Poetry, art, history. He was just very nice to everybody. And truly seemed very interested in the books. It wasn't like someone was picking things out for him," added Gloss.