The castle's core is the center of Laputa's ancient knowledge and weapons, which Muska activates using Sheeta's crystal, revealing to her that he is also a descendant of the Laputan royal line.

[8] The film was never produced, but it inspired Miyazaki's longtime collaborator Isao Takahata to create The Story of Yanagawa's Canals (1987), a documentary on the environmental effects of industry on the local waterways.

Miyazaki chose the name himself,[12] referencing both the Arabic term for a warm wind from the Sahara, as well as the Caproni Ca.309 Ghibli, an aircraft used by the Italian military during the Second World War.

[13] The intent behind the creation of the studio was to "blow a whirlwind" into a stagnating Japanese animation industry by creating original, high-quality feature films.

[14] In a speech at the 1995 Annecy International Animation Film Festival, Suzuki said "The idea was to dedicate full energy into each piece of work with sufficient budget and time, never compromising on the quality or content.

Their ultimate failure to preserve the industry left a lasting impact on Miyazaki, who viewed the event as an attack by those in power on the miners' way of life and the hard-working spirit of the people.

[12] His experiences are reflected in several supporting characters in the film, who despite laboring through poverty in the mines, enthusiastically protect the protagonists from multiple aggressors.

"[20] Many of Miyazaki's old colleagues as well as much of the production crew of Nausicaä of the Valley of the Wind were employed once again to work on Castle in the Sky at Studio Ghibli's inception.

"[24] However, in contrast with the more optimistic conclusions of Miyazaki's previous works, Napier notes that the film ends with an "unsettling view" of the castle flying away, suggesting that humanity may not deserve to exist in the natural world.

"[26] Lioi notes that this outlook differs from dominant Western ideas, eschewing the extremes of capitalism and industrialism, as well as radical environmentalism and conservationism.

"[29] Lioi argues that Laputa is used as a means to comment on the ethics of contemporary culture,[26] based on Ildney Cavalcanti's observation that such a utopia also "must contain an overtly dystopian element, such that the implicit critique in utopian discourse becomes explicit.

[41] Additionally, unlike Miyazaki's previous works, the protagonists do not succeed at convincing the antagonists of their wrongdoing, which offers a more pessimistic view on children's ability to educate others.

[41] Napier proposes that Miyazaki's insistence on showing the freedom of children in Castle in the Sky can be credited to the influence of Panda and the Magic Serpent (1958).

[42] At a lecture given in 1982 at Waseda University, he said "When I saw Panda and the Magic Serpent, it was as if the scales fell from my eyes; I realized that I should depict the honesty and goodness of children in my work."

[34] A variety of fictional flying machines appear across the film, including the island of Laputa, the airships, and the pirates' ornithopters; Sheeta's crystal also allows her to float through the air.

"[48] Commenting on the mecha anime popular at the time, Miyazaki expressed his hatred for shows that glorified machines without portraying the characters struggling to build or maintain them.

[51] Napier writes that Verne's impact on the film's style was instrumental in evoking imagined nostalgia for a time when "machines were still fun", in Miyazaki's words.

[53] Miyazaki stated that, as a child, he was attracted to the design and power of military planes, a view that has since been replaced with revulsion for the indiscriminate acts of violence that the machines have been used for.

[59] The film later earned a significant additional amount through rereleases;[14] as of 2021[update], it has grossed approximately US$157 million in box office, home video, and soundtrack sales.

[72] Due to the possible confusion of the title with the Spanish phrase la puta – literally 'the whore' – the film was released as simply Castle in the Sky in North America.

[78] Three months before the film's theatrical release, the image album – a collection of demos and musical sketches that serve as a precursor to the finished score – was published by Tokuma on compact disc.

Though Hisaishi felt that American film scores used an overly simplistic compositional approach, he commented "But when I redid the music of Laputa this way, I learned a lot.

"[80] The credits sequence of the film features an original vocal song titled "Carrying You" performed by Azumi Inoue, with music by Hisaishi and lyrics by Miyazaki.

The site's critic consensus reads, "With a storytelling palette as rich and brilliant as its animation, Castle in the Sky thrillingly encapsulates Studio Ghibli's unique strengths.

Club's Tasha Robinson calling Disney's recordings "almost comically bland",[93] and Conrad expressing his appreciation for Anna Paquin as Sheeta and Mark Hamill's performance as Muska.

[4] Many critics also praised the animation,[94] the Asheville Times's Tom Sabulis considering it "state-of-the-art"[95] and The Philadelphia Inquirer's Steven Rea naming it "masterful".

[101] A reviewer for City Road noted that the film could present themes that were critical of modern society while still maintaining a "warm and caring" view of humanity.

[112] Along with Nausicaä of the Valley of the Wind, Philip Boyes of Eurogamer considers Castle in the Sky a major contributor to the genres' popularity in Japan, introducing audiences to stylistic features such as airships which were otherwise mostly prevalent in Europe.

Nadia: The Secret of Blue Water (1990), by Neon Genesis Evangelion director Hideaki Anno, is noted for its similarities in premise with Castle in the Sky.

[123] On December 9, 2011, during an airing of Castle in the Sky on Japanese television, fans posting to Twitter set a new record for the platform by causing a peak of 25,088 tweets per second.