Secret Route
Go to the sewer in the city. Find the two crooks and make sure that Pac Man is very mad. Go into the hole. Then if Pac Man is not mad, he will come out and fall down in pain. If he is mad, he will come out in pain, but regain his strength, get mad and chase them out. Then you'll see where they went through the wall. Shoot the wall and Pac Man will go through it. You'll be on a mine cart ride.