updated 09/21/2011 AT 4:50 PM ET
•originally published 09/21/2011 AT 11:15 AM ET
Two weeks after doing Disneyland on a casual date, the pair were spotted hiking on the grounds of L.A.’s Griffith Observatory on Sunday – bringing a little extra star power to a place known for more celestial star-gazing.
“Eva wasn’t dressed for the dirt road hike and she walked slowly in her sandals,” an eyewitness says. “Ryan didn’t seem to mind the slower pace and they both looked very happy.”
Gosling, 30, and Mendes, 37, recently filmed the drama The Place Beyond the Pines together, and are now quietly dating off-screen. Gosling is currently filming The Gangster Squad in L.A., where he’s also clocking time with Mendes.
“[He] visits Eva at her house as often as he can,” a source tells PEOPLE, adding that the two have been staying in – and hanging out.
“The couple have enjoyed many quiet nights with delivery food,” says the source, “and have also been spotted on casual strolls in Eva’s Los Feliz neighborhood.”
Reporting by PERNILLA CEDENHEIM