Much of the early colonial art stemmed from the codices (Aztec illustrated books), aiming to recover and preserve some Aztec and other Amerindian iconography and history. From then, artistic expressions in Mexico were mostly religious in theme. The Metropolitan Cathedral still displays works by Juan de Rojas, Juan Correa and an oil painting whose authorship has been attributed to Murillo. Secular works of art of this period include the equestrian sculpture of Charles IV of Spain, locally known as El Caballito ("The little horse"). This piece, in bronze, was the work of Manuel Tolsá and it has been placed at the Plaza Tolsá, in front of the Palacio de Minería (Mining Palace). Directly in front of this building is the beautiful Museo Nacional de Arte (Munal) (the National Museum of Art).