The Diocese of Vigan is a Roman Catholic diocese located in the Philippines, specifically in the province of Ilocos Sur. Established in 1581, it is one of the oldest dioceses in the country. The diocese is part of the ecclesiastical province of Archdiocese of Nueva Segovia and serves a diverse population through various parishes and missions. The diocese's seat is the Vigan Cathedral, also known as the Cathedral of Saint Paul the Apostle. This historic church is a significant landmark in the city of Vigan, which is recognized for its well-preserved Spanish colonial architecture and is a UNESCO World Heritage Site. The diocese plays a vital role in the spiritual and community life of its residents.