Hilton Hotels heiress Nicky Hilton is engaged to her boyfriend of three years, James Rothschild. According to people close to Rothschild, he proposed last weekend while the two were vacationing in Italy.

"They went on a romantic anniversary trip over the weekend," a source told US Weekly. "He took her out on a boat into the middle of Lake Como and he proposed, got down on one knee and everything. It was incredibly romantic and beautiful."

Hilton has not commented on her engagement, but her sister confirmed the news on Instagram.

"Congratulations @NickyHilton on your engagement. I'm so happy for you! You will be the most beautiful bride! Such a lovely couple! Love you both so much," Paris Hilton posted along with a picture of the couple.

Nicky and Rothschild, the heir to a European baking family, first started dating in 2011 after meeting at a friend's wedding. It turns out that Rothschild has a very romantic side. He took the 30-year-old back to where they first met, Italy, to pop the question.

No word on yet on a wedding date or where the couple plans on tying-the-knot. In addition to planning her nuptials, Nicky is preparing to release her book, "365 Style," on Sept. 2. Nicky and Rothschild haven't made it back to the states yet.

A source told US Weekly that the two are still vacationing and are taking "a road trip now throughout Europe."