Puerto Limon is the country's most important port. It was built on the site of an old Indian village called Cariari. At this place actually Columbus landed on his last voyage to this continent.Many travelers bypass Limn completely -- the beaches to the south beckon, after all -- but the city deserves a look. Christopher Columbus first set foot here in 1502. You can, too! Most of the habitants of the city are black. Visitors should see the palm promenade and tropical flowers of the Parque Vargas. As you are in the Caribbean you should take part in Limon's nightlife, but beware of strolling around alone at night.
Limon is also a good base to to some interesting trips to some of Costa Rica's natural parks. Visit the Cahuita National Park & Puerto Viejo, the Gandoca Manzanillo Wildlife Refuge. If you are into sports go biking or snorkeling in Punta Uva Hitoy-Cerere Biological Reserve.
All in all, many travelers bypass Limn completely the beaches to the south, but the city deserves a look.