Muntinlupa City Charter Day, observed in the City of Muntinlupa, Philippines, is celebrated every March 1 to commemorate the city's chartering as the 65th city of the Philippines. This special non-working holiday recognizes Muntinlupa's rich history, which dates back to the Spanish colonial era, with its original settlement founded in 1601. The city's name is believed to derive from various sources, including the Tagalog phrase "munting lupa," meaning "little soil," and the Spanish word "monte," meaning "mountain." Muntinlupa, known as the "Emerald City" for its green spaces, was officially designated a city on March 1, 1995. The celebration is marked by local festivities and activities, reflecting the city's cultural heritage and community spirit. Muntinlupa City Charter Day was formalized by Republic Act No. 9191, signed into law in 2003, and is unique to the city, not celebrated elsewhere in the country.