El Águila Real doesn’t have a lot in common with Nick’s Restaurant, the iconic State Street diner it replaced earlier this year. Nick’s, a Greek-inspired diner open since 1959, served burgers, gyros, fish fry and patty melts. By the time it closed in spring after more than 60 years, Nick’s had served stars like Joan Baez, Johnny Cash, Julia Louis-Dreyfus, Roger Ebert and Lenny Kravitz, according to a 2009 Isthmus story.