They walked by the Trevi Fountain, stopping to check out the incredible landmark, where the couple cheekily stole a smooch among the admiring crowd of people.
Lauren stunned in a vibrant red, backless halter mini dress.
She had her long, dark hair loosely pulled back into a ponytail and paired her look with slip-on beige heels. They couldn’t keep their hands off each other and put on an affectionate display – with Lauren’s dazzling diamond ring in full view.
The couple have been enjoying a European summer together, first spotted in Greece on their yacht in June.
Earlier this week, the billionaire and his fiancée were pictured soaking up the sun in Italy last week with an A-list cadre of guests, including Leonardo DiCaprio, his girlfriend Vittoria Ceretti, and Katy Perry and Orlando Bloom.
The celebrity couples were snapped as they disembarked from a tender boat at Nikki Beach on the island of Sardinia.
