Katy Perry, Reese Witherspoon and Emma Roberts Lead Today’s Star Sightings

As America gears up for the Fourth of July, Celebuzz is rounding up the hottest star sightings from the past 24 hours.

Katy Perry looked vacation ready as she was spotted out in East Hampton, New York with a bike in tow. The 28-year-old singer donned a cute jumpsuit and headscarf as she headed out for the day with a friend.

On the west coast, Reese Witherspoon squeezed in a workout at Burn 60 gym in Brentwood, Calif. while Emma Roberts looked stylish in a blue dress while running errands in Los Angeles.

Over in Italy, Ian Somerhalder filmed a sexy perfume campaign with Ana Beatriz Barros. The shoot, which took place at Como Lake (George Clooney’s favorite), was for a new scent by Azzaro.

Other international sightings include Nicky Hilton celebrating the Lancome Show by Alber Elbaz in Paris, Nicole Scherzinger (and her amazing abs) arriving at the Cardiff auditions for X Factor UK and model Petra Nemcova looking lovely in Elie Saab at Paris Fashion Week.