The Monument to the Heroes of the Restoration of the Republic (Av. Monumental, 9 a.m.–5:30 p.m. Tues.–Sun., closed Mon., RD$60) is hard to miss. Not because it has such interesting features inside or because it has a good exhibit. No, it is literally hard to miss. It is an eight-story tower, five of which are devoted to the museum, perched on top of a tall hill overlooking all of Santiago [1].
Trujillo had commissioned that it be built in honor of himself (in classic Trujillo egoism), but when the dictator was assassinated, it was rededicated to honor those who died in the Restoration War. The museum and grounds were completely renovated in 2007, giving it a more welcoming feel than the previously grungy and unfinished one.
Outside in the plaza are collections of bronze statues depicting noteworthy Dominicans like artists and ball players, along with palm trees and a gorgeous sprawling lawn (and lots of wandering treat vendors).
The museum is dedicated to Dominican history and the history of the restoration. At dusk this is a wonderful spot to come and watch the sunset and have a beer, which you can buy from the vendors. From here you can see the entire city and surrounding mountains, a truly spectacular view.
Links:
[1] http://www.moon.com/destinations/dominican-republic/el-cibao/santiago