For an algebraic function field F having a finite constant field, let g(F) (resp. N(F)) denote the genus of F (resp. the number of places of F of degree one). We construct a tower of function fields F-1 subset of or equal to F-2 subset of or equal to F-3 subset of or equal to... over F-q2 such that the ratio N(F-i)/g(F-i) tends to the Drinfeld-Vladut bound q - 1.