Simpson and her boyfriend, John Mayer, took a "Roman Holiday" together and held hands around the streets of the city.
It has been claimed Ashlee Simpson has been coping with her break-up by picking up men.
The former "Baywatch" star split from rocker Dave Navarro in 2006 and divorced in February.
Cameron was recently seen kissing model Tyrese.
The ditzy singer and actress has referred to antics enlisted by Paris Hilton, Lindsay Lohan and Britney Spears for attention, saying she would never leave the house without her underwear.
The couple, who have been traveling together on Mayer's national tour, are officially an item after months of speculation - and the singer/songwriter is happy about it.
"RuPaul's Drag Race" Season 6 Premiere Party - Arrivals
86th Annual Oscars Nominee Luncheon - Arrivals
MKTO in Concert at Q102's Performance Theatre in Bala Cynwyd - February 21, 2014
Kim Kardashian and Kanye West agree prenup
Angelina Jolie and Brad Pitt don't want their children to act
Justin Bieber back with Selena Gomez?
Lindsay Lohan has Oprah Winfrey on speed dial
Jennifer Lawrence unchanged by fame
U2 album won't be released until 2015
Justin Bieber's mother wants more children
Jamie Dornan learns to walk heel to toe
Katie Holmes praises inspirational mother
Sir Richard Branson can't wait for Lady Gaga's space outfit
Oprah Winfrey gives dress to Twitter fan
Jourdan Dunn awestruck by Beyoncé