Tiny North End raw bar Neptune Oyster is famous, and a long wait for seats is typical. The hype is justified: Dozens of shellfish line the icebox at any given time. Temptingly fresh and lovely to look at, the selection runs the gamut from East and West Coast oysters to Maine sea urchin and Massachusetts cherrystones. A seat at the counter provides excellent shucking theater. Among other must-try seafood dishes like the caviar-topped Johnnycake and lobster rolls, Neptune also serves up one of Boston’s most decadent plate of oysters: “Piggyback,” which tops a slice of blueberry cornbread with a fried oyster, Berkshire pulled pork, and maple-walnut butter.