English · Idiom Attested

build castles in the air

In real, traceable use. Part of the curated seed collection; community review is coming.

Both English Tiếng Việt

Meaning · English

Have unattainable scheme.

Nghĩa · Tiếng Việt

có kế hoạch không thực tế

Machine-translated — suggest a fix

Where it’s used: Used Widespread English

Examples

I remember the days when, as a small child, I was taken around boatyards, harbours and rivers to admire boat after boat, while he built castles in the air about owning one.

British National Corpus sentence via the MAGPIE corpus (CC BY 4.0, retrieved 2026-07-30)

Sources & notes

Listed in Wiktionary’s “English idioms” category (retrieved 2026-07-29); definition pending editorial review. Figurative class: Euphemism (PIE-English corpus, CC BY 4.0, retrieved 2026-07-31).

Common questions

What does “build castles in the air” mean?

Have unattainable scheme.

Is “build castles in the air” formal or informal?

No register label has been reviewed yet — treat it as neutral and check the usage notes above.