The only ecclesiastical edifice thus far restored is the tiny hilltop Ermita de Potosí (Potosí Hermitage, Calzada Vieja Guanabacoa, esq. Calle Potosí, tel. 07/797-9867, daily 8 a.m.–5 p.m.), the highlight of a visit to Guanabacoa [1]. The simple hermitage dates back to 1644 and is the oldest religious structure still standing in Cuba. It has an intriguing cemetery.
Links:
[1] http://www.moon.com/destinations/cuba/havana/sights-across-the-harbor/guanabacoa