The Plazuela Real del Jigüe is a charming triangular plaza (Piro Guinart y Villena), one block west of Plaza Mayor [1], has a calabash tree in the center. The tree, planted in December 2009, is the youngest in a succession of trees kept alive since 1514, the year the Spanish celebrated their first mass here.
Cater-corner to El Jigüe is the Ayuntamiento y Cárcel (Piro Guinart #302), the old town hall and jail, with a portion of the original stone-and-lime masonry exposed for view.
Immediately east, the Casa Templo de Santería Yemayá (Villena #59) features santería altars and hosts occasional religious ceremonies. Jorge Muñoz Fontanills (Simón Bolívar #302, e/ Martí y Maceo) will happily show you his fascinating collection of orisha statues.
Links:
[1] http://www.moon.com/destinations/cuba/sancti-spiritus-province/trinidad/sights/plaza-mayor