"Bolshoi" in Russian means "big," and Moscow's 228-year-old institution is grand in many ways. The company, which will perform at Northrop this week with some 100 dancers and the equally venerable Bolshoi Orchestra, has an illustrious history and singularly defines, for many dance lovers, traditional ballet history and technique. Still, all has not been well for the Bolshoi in recent years. Financial and political challenges created a tense atmosphere, but much seems on the mend with the arrival of 36-year-old Alexei Ratmansky, who took over as director earlier this year. Already the troupe has taken some chances, including the 2003 re-imagining of the classic ballet Romeo and Juliet (Friday at 8:00 p.m.) as a contemporary work, directed by Brit Declain Donnellan, known for his groundbreaking Cheek by Jowl troupe. Forget about the pointe shoes and tutus. In Donnellan's version we see a cross between West Side Story and other contemporary updates on the doomed love theme, with the performers offering a fresh perspective that's still driven by the Sergei Prokofiev score. For those who like their Bolshoi pure, however, the company will also perform Don Quixote (Saturday at 8:00 p.m.; Sunday at 1:00 p.m. and 7:00 p.m.), first created some 150 years ago and featuring nearly 20 soloists and character dancers alone. They've performed this work nearly 1,000 times, and everything from the costumes to the music is dripping with lush authenticity. There's probably more dance stuffed into this extravaganza set to a score by Ludwig Minkus than any other ballet, so settle in for a long night. This is one of the cases where big certainly means better. $37.50-$73.50.