I would ask anyone of them this question "In which direction your would twin point if I ask him the way to the town?"
And I would go in the direction not pointed by him.
Case 1) Suppose I go to the truth telling twin and ask this question. He knows that his liar twin points the wrong route and he points out the same wrong one(Now, observe that he is truthful because he showed the route his liar twin would show).
Case 2) Suppose I go to the liar twin and ask this question. He knows that his truth-telling twin would point out the right direction but this liar points out the false direction because he should lie.
Now see, both the twins pointed out the false direction.
So, I shall take the path not pointed by the either of the twins.