build castles in the air
Meaning
To make unrealistic plans or daydream about grand ideas that are unlikely to happen.
Origin
From an older image of constructing castles in the air—impressive but impossible. It appears in English by the 16th century and parallels similar expressions in French.
Notes
Often mildly critical or cautionary, implying the plan lacks realism or evidence. Used in speech or writing. Can sound dismissive if said about someone’s dreams, so soften when needed.
Examples
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Without a budget or a timeline, we’re just building castles in the air.
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He keeps building castles in the air about becoming famous overnight.
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It’s fine to dream, but don’t build castles in the air and ignore the risks.
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They were building castles in the air, planning a luxury trip before they’d saved a dime.
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If we don’t get approval from legal, this proposal is just building castles in the air.
Grammar & Usage Notes
Fixed phrase: “build castles in the air” (also “in the sky”). Verb inflects (build/builds/built). Often used with progressive (“is building…”) or as a clause (“don’t build…”).
Synonyms
- daydream
- have your head in the clouds
- pipe dream
- build air castles
- indulge in fantasy
Antonyms
- be realistic
- keep your feet on the ground
- make practical plans
- face reality