Lucas conceived "Raiders of the Lost Ark" in the early 1970s. Seeking to modernize the serial films of the early 20th-century, he developed the idea further with Kaufman, who suggested the Ark as the movie's goal. Lucas eventually focused on developing his 1977 space opera "". Development on "Raiders of the Lost Ark" resumed that year when Lucas shared the idea with Spielberg; he joined the project several months later. While the pair had ideas for significant scenes in the movie, they hired Kasdan to fill in the gaps between them. Principal photography began in June 1980 on a $20 million budget. Filming took place on sets at Elstree Studios, England, and on location in La Rochelle, France, Tunisia, Hawaii and California.