Cathedral of San Marcos
is designed by Gustave Eiffel of the eponymous Tower in Paris. It's a popular attraction. Entry is from Plaza Colón.The views from el Morro are superb. One can follow the work being done in the harbour closely or gaze at the mountains gradually turning into the altiplano in the east. The hill looks like a giant sand dune from a distance but it is in fact made of solid rock. The paved footpath visible from anywhere in town starts at the south end of Calle Colón. Allow 10 minutes for walking up and enough time for philosophic discussions on top. There is a war museum on the hill for those into uniforms and cannons from the 19th century. Beware of the dishonest Coca Cola vending machines, bring water and snacks from town.