Hi Thoufiq, Things to do in Manila:
1. Visit Intramuros. This heritage site consists of 6-7 forts all built by the Spanish during World War 2 and can take up one full day if you visit each one, however, the most famous ones include The Manila Cathedral , Fort Santiago.
2. One of the best ways to know a city is through its museums and Manila has lots of them. Visit museums like Metropolitan Museum of Manila, Ayala Museum.
3. Go Shopping in The Mall of Asia, who doesnt love to shop anyway!
4. Visit The City of Dreams. Its the biggest casino in Asia and worth a visit, who knows the odds might be in your favour ;)
5. Take a walk by the Manila Bay.
I have attached a couple of stay options and an article on Manila, go through them for more information