Heredia and it's location at the slopes of the mystical Barva Volcano give the small town an appealing atmosphere and views. Coffee plantations and the National University give the town a busy demeanor but behind the scenes, it is a slow pace and very relaxing.
You can find a variety of historical sights to look in on, have lunch in great little cafe's and venture up to see the sights at the volcano. Sights to add to your list is the Casa de la Cultura, housing a small museum and take a stroll through the Basillica de la Immaculada Concepcion. This area is referred to as the City of Flowers and touring some of the local gardens gives you an idea why.
Photo Credit: By Rafael Nájera (Rnajera: English, Español, Français) (Own work) [GFDL or CC-BY-SA-3.0], via Wikimedia Commons