Born in Denmark in 1873, Peter Nielsen emigrated to Chicago in 1887. He studied at the Art Institute of Chicago (AIC) , but is considered mostly self taught. He moved to the Los Angeles area in the 1920's, and remained there the rest of his life. He was first exhibited at the AIC, but later exhibited in California. His paintings are held at the Oakland Museum of California and the Los Angeles County Museum of Art. He was co-artist on a mural with Ejnar Hansen which is in the Fiesta Room of the Biltmore Hotel in Los Angeles. He is noted for his landscapes and still lifes.

An interesting story involves a commission for a mural by Edgar Payne in 1917. Payne was asked by the Congress Hotel inChicago to provide murals for all eleven floors of their new hotel. To get the job done, he and his artist wife Elsie Payne hired other artists, Jack

Wilkerson Smith, Peter Nielsen, and Grayson Sayer. They rented a warehouse in the town of Tropico (now Glendale) near Eagle Rock. In Eagle Rock, a young artist named Conrad Buff heard of the project and applied for an assistant's position at $3.50 per day. Buff would stretch the canvases. Payne would then sketch out the painting. Buff would paint the sky and clouds, Payne and Smith would paint the foreground, Nielsen painted garlands and garlands of flowers, and Sayer and Payne would finish the foreground. By the end of the job, Buff was making $5.00 a day, eleven square yards of muslin were used, and ten thousand pounds of white lead paint.

Source: Libby Buff and George Stern, The Art and Life of Conrad Buff, 2000., Artists in California 1786 - 1940, Edan Milton Hughes, 3d ed.