Celeb Sightings! See Where Your Favorite Stars Hung Out This Week

Sophia Bush Credit: Christopher Neseman

--Sophia Bush cheering on good friend Betty Who during her performance at the Gilt City Better Than Backstage Rooftop pool party during Lollapalooza weekend in Chicago.

--Helen Mirren chatting with Oprah during a cast dinner at Monkey Bar after premiering their film The Hundred-Foot Journey at the Ziegfeld Theater in NYC.

--Jimmy Fallon buying an array of Farm Candy products while shopping with his family at the Hamptons Collective in Bridgehampton, N.Y.

--Tiffani Thiessen wearing her San Diego Hat Company's Raffia Stone Fedora during a family trip on the lake in Hill Country, Texas. 

--Rapper NAS giving a surprise performance featuring works by Shepard Fairey at the launch of his limited edition Hennessy V.S. bottle at the Art Alliance in Chicago.

--Taylor Schilling sparkling in One Jewelry earrings at the Orange Is the New Black panel discussion in L.A. 

--Jamie Foxx and Amber Rose twerking on stage and throwing back Ketel One cocktails to a special rendition of "Gold Digger" at the new Hyde Sunset Kitchen + Cocktails in L.A. 

--Christina Milian rocking out to her new LG Electronics Bluetooth headset at Drais in Hollywood.

--Nikki Reed working on her grocery list during the official launch of Vita Coco Coconut Oil at Haven's Kitchen in NYC.

--Illumination Road, Grace Harris and Carly Tefft performing an acoustic rock night at the House of Blues' Voodoo Lounge in West Hollywood.

--True Blood's Ryan Kwanten having a date night with girlfriend Ashley Sisino at a Beekeeper Wine Dinner at Del Frisco's Grille in Santa Monica, CA.

--Megan Fox chatting with couture jewelry designer Margaret Rowe - wife of producer Bret Rowe - at the Teenage Mutant Ninja Turtles premiere in Westwood, CA.

--Irish actress Victoria Smurfit supporting her husband at the 10th Anniversary party of M&C Saatchi produced by The Admirable Crichton events in Santa Monica, CA.

--Jay Glazer giving friend Michael Strahan a bottle of Johnnie Walker Blue Label to celebrate his Pro Football Hall of Fame induction in Canton, OH.

--Robert De Niro sampling the tasting menu during a romantic dinner with wife Grace Hightower at The Musket Room in NYC.

--Don't stop believing! Constantine Maroulis returning to the Broadway stage in Rock of Ages in NYC.

--Rascal Flatts admitting they've all suffered from frequent heartburn during a press day to promote their partnership with the new Nexium 24HR in NYC.