El Fortín is Heredia's most distinctive landmark — a cylindrical stone tower rising just north of the Parque Central, the remains of a military headquarters that was abandoned before completion. The tower is modest in scale but unmistakable in silhouette, and its story is part of the local identity: built with the rifle loopholes facing the wrong way, it was useless as a defensive structure from the moment the walls went up.
The fortín is a national monument and cannot be entered, but it is worth a short detour to see it from the outside. It stands in a small garden area, slightly removed from the main square, and the combination of the tower and the colonial church visible from the same vantage point gives the best sense of Heredia's nineteenth-century civic character.