Lal-lo, officially the Municipality of Lal-Lo (Ibanag: Ili nat Lal-lo; Ilocano: Ili ti Lal-lo; Tagalog: Bayan ng Lal-lo), is a 1st class municipality in the province of Cagayan, Philippines. According to the 2020 census, it has a population of 48,733 people.  During the Spanish colonial period, Lal-lo was known as Ciudad de Nueva Segovia and was the seat of the Diocese of Nueva Segovia before it was moved to Vigan in Ilocos Sur. It is currently under efforts to regain its Spanish-era city status.