Intramuros with kids: Fort Santiago and San Diego Gardens
First of all, to get to know Intramuros, I highly recommend Carlos Celdran's walking tour. He does an amazing job of going over Manila's history from Chinese to post-WWII times in a theatrical tour. He passionately gives his audience an appreciation and understanding of how Manila came to be the way it is today. See his blog for tour dates/rates:
Two places in Intramuros that are particularly kid-friendly below. If you need a place to dine, we love Ristorante delle Mitre which is like an old Spanish bistro, for it's quaintness and old spanish/filipino food at very reasonable prices (we like the pancit, the fresh lumpia, the kangkong and okra dishes... and any pasta and the fried chicken for the kids. Their desserts/tarts are good too!)
1) Fort Santiago: Old fort with manicured lawns. Kids can enjoy the grass and greenery, climb on old ruins, and walk the steps of Jose Rizal. Entrance fee is PHP75 for adults, 50PHP for kids. Open daily 8am to 5pm.
2) San Diego Gardens: Gardens connected to one of the baluartes (bastions) of Intramuros. The remains of the bastion itself are impressive and surrounded by an area of green where kids can run around and balance on ruins. In what felt like a hidden garden, kids can explore: potted plants, flowers, leafy archways, bonsai trees, and the walls of Intramuros. We went at 9am on a weekday and had the place pretty much to ourselves. It was quiet and fun to explore this rudimentary secret garden with a backdrop dripping with history. Entrance fee is PHP75 for adults, 50PHP for kids. Open daily 8am to 5pm.