Here are some of the top Spanish forts in the Philippines that I have visited.
1. Fort Santiago, Intramuros, Manila (famous for its role in history)
2. Fort Pilar, Zamboanga City
The Royal Fort of Our Virgin Lady of the Pillar of Zaragoza (commonly known as Fort Pilar) is a 17th century military defense fortress in Zamboanga City.
Related link - http://junvillegas.blogspot.com/2013/01/the-great-sta-cruz-island-zamboanga-city.html
3. Fort San Pedro, Cebu
4. Fort Santiago, Ozamis City
5. Fort San Antonio Abad, Malate, Manila