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 film's goal. Lucas eventually focused on developing his 1977 space opera "Star Wars". Development on "Raiders of the Lost Ark" resumed that year when he shared the idea with Spielberg who joined the project several months later. While the pair had ideas for notable scenes in the film, they hired Kasdan to fill in the gaps between them. Principal photography began in June 1980 on a $20million budget. Filming took place on sets at Elstree Studios, England, and on location in La Rochelle, France, Tunisia, Hawaii and California.