tsp-solve is a C++ code by
Chad Hurwitz and Robert Craig with and provides both heuristic and optimal
solutions.
Geometric problems of size up to 100 points are managable.
It is available by emailing Chad Hurwitz at churritz@cts.com,
and below on the algorithm repository.
A heuristic Euclidean TSP solver in C due to Lionnel Maugis
is available from http://www.cenaath.cena.dgac.fr/~maugis/tsp.shar .