THE FIRST THING you need to remember when going into a Martin Scorsese film is that it’ll probably be long. Get food and drink. Go to the bathroom. Wear comfortable clothing. In fact, the last movie Scorsese made under 2 hours was released in 1986 (“The Color of Money,” at 119 minutes). Ever since then, his epics have averaged a running time of 2 hours and 20 minutes (his longest is 1995’s “Casino,” at 2:58). His second-longest film? “Gangs of New York,” the director’s latest epic about the city’s turbulent history from the gangland turf wars of lower Manhattan in the 1840s culminating in the notorious Draft Riots of 1863.

But a long running time isn’t necessarily a bad thing, especially when trying to tackle twenty years of violence and strife in a New York none of us recognizes. Save for a few street names (particularly Canal and Mulberry), Lower Manhattan in the mid-19th century was not so much a city as it was, in Scorsese’s own words, “the Wild West in closed confines.” Violence was a savage daily occurrence, corruption was rampant (city corruption still exists, but hardly as blatant as during the reign of Boss Tweed and Tammany Hall). And poverty levels were astounding. At one housing complex, babies were supposedly dying at an annual rate of roughly 33 percent–some eaten alive by sewer rats the size of cats.