Although he studied and exhibited abroad and his works can be found in collections in various parts of the world, Cuéllar dedicated most of his career in his studio in San Miguel de Allende.

Nicolás Cuéllar was an artist,[2] who was born and lived his entire life in the same house in the center of San Miguel de Allende (2ª.

[3] Every day the painter would leave his home in San Miguel de Allende to spend time in the main plaza of the city, after painting for several hours in the morning.

[3] The house hosted a small gallery and studio, where an old Singer sewing machine table covered in a hand painted cloth served as the reception desk.

The first was at the New York Methodist Hospital in 1963 and the second is at the Hermanos Aldama Elementary School in San Miguel de Allende, created in 1971 and restored in 2000.

[5] Cuéllar taught art at the Academy of San Carlos and at the Instituto Allende but later in his life he stopped working with institution, but continued to have private students.

His inspiration fountain had many manners, styles, interpretations and sizes, some of them obsessions: one was the towers of his main church´s town (San Miguel Archangel Church), which represent one of the center of his universe, the lands of his brain, to his veins.

His works shows a mixture of pre Hispanic, fantasy and Biblical elements, drawing on Mexican folklore and the mysticism of medieval Europe.

[4] His work has been compared to Bosch, and he stated that his influences included De Chirico, Brugel, Monet, Laktionov and William Lake.

[2][3][4] This focus took root after his return to Mexico in the 1960s, when he began to paint medieval themes in somber tones, witches, prostitutes, magicians, astronomers, clergy along with peculiar and fantastic figures such as men and women with multiple heads.