Intramuros is so special because back when the Philippines was getting colonized by Spaniards, it played a special role such as being the seat of Spanish government. It served as the Spaniards' political and military base in Asia and its whole area is a world heritage site
References:
https://theculturetrip.com/asia/philippines/articles/the-history-of-manilas-walled-city-of-intramuros/
https://www.afar.com/places/intramuros-manila-2#:~:text=Intramuros%20plays%20an%20important%20part,when%20they%20colonized%20the%20Philippines.
https://www.tripadvisor.com.ph/ShowUserReviews-g298573-d548076-r177924369-Intramuros-Manila_Metro_Manila_Luzon.html