Welcome to Mission Dolores State Historic Site. Misión Nuestra Señora de los Dolores de los Ais was a Spanish mission built in 1721 along the El Camino Real de los Tejas. Visitors are invited to explore the site’s rich history at the museum, which tells the history of the Spanish in East Texas. Stroll along the El Camino Real walking trails and enjoy the real sights and stories of this real place in East Texas. The site also has an RV park, picnic areas, and group pavilions.