San Marcos is sort of the hub of the Pueblos Blancos  and hosts Nicaragua’s best (and most expensive) university, the Ave Maria College of the Americas (three blocks south of the park, www.avemaria.edu.ni ), a Catholic, bilingual, four-year liberal arts university with about 400 students and a sister campus in Ann Arbor, Michigan.
Before 1998, its modern facilities belonged to the University of Mobile (Alabama). Ave Maria is one of the beneficiaries of Catholic conservative and Domino Pizza founder, Thomas Monaghan. Not much to see here other than the church and town square, both of which are lovely.
There’s one hotel: Hotel Casablanca (two blocks east of the church’s southeast corner, tel. 505/2535-2717, $46–55), with Wi-Fi, hot water, breakfast included. There are several small restaurants; La Casona (near the park) is particularly recommended for its food and pleasant owner.