Which team completed the only perfect season in NFL history, including the Super Bowl, in 1972?

Which Super Bowl was the only one not designated with Roman numerals? Which two leagues merged in 1970 to form the modern NFL? In which city was the NFL founded in 1920, as the American Professional Football Association? In which city is the Pro Football Hall of Fame located? Which team went 16-0 in the 2007 regular season but lost the Super Bowl? Which team went 0-16 in the 2008 season, the first team to do so? Which team went 0-16 in the 2017 season? Which Super Bowl featured the largest comeback in Super Bowl history, from a 28-3 deficit?