Castles in the Air Idiom: Meaning, Origin, Usage & Exercises

When people dream about things that are nearly impossible or have little chance of being achieved, they are said to be building ‘castles in the air’. The phrase remains popular in literature, speeches, and even academic discussions because it beautifully captures the concept of chasing illusions.

In this blog post, we will explore the meaning, origin, and usage of the idiom ‘castles in the air’ and provide examples from the IELTS exam.

Castles in the Air Idiom: Meaning

The idiom ‘castles in the air’ means having unrealistic plans, ideas, or hopes that are unlikely to materialize. It reflects ambition without practicality or vision without grounding in reality.

Origin of Castles in the Air Idiom

The idiom dates back to 16th-century Europe, with the earliest recorded usage in French as “châteaux en Espagne” (castles in Spain), referring to impossible dreams since Spain was considered a distant, almost mythical place at that time.

• The English phrase ‘castles in the air’ was popularized by writers like Samuel Johnson (1750s) and later by Henry David Thoreau in “Walden” (1854), who used it positively: “If you have built castles in the air, your work need not be lost; that is where they should be. Now put the foundations under them.”

Thus, historically, the idiom has been used both negatively (unrealistic) and positively (imaginative but worth pursuing).

Castles in the Air Idiom Usage

Given below are some example sentences that show how the ‘castles in the air’ idiom can be used appropriately for a higher IELTS band score. 

•  I really want to become a famous Hollywood actor, but I realize that it’s just a castle in the air and that I shouldn’t quit my day job.
• Sometimes you feel that your hopes and ambitions are just castle in the air. But hold on to your dreams; one of them will soon come true.
• Before you start building castles in the air, just think how much all this is likely to cost.
• Ravi spends hours talking about his business ideas, but most of them are just castles in the air.
• Believing she could complete the entire syllabus in a single night was nothing more than building castles in the air.
• Politicians often sell castles in the air during election campaigns to attract voters.
• Proposals to eliminate global poverty overnight may sound inspiring, but they are often castles in the air without sustainable policies.
• Without proper funding, the company’s expansion plans are castles in the air.

Castles in the Air Idiom: Synonyms and Related Phrases

Listed in the table that follows, you will discover a selection of the best phrases to use in IELTS Speaking responses related to the idiom 'castles in the air'.

Castles in the Air Idiom: Detailed Usage in IELTS Contexts

Let us explore a few different ways in which the idiom ‘castles in the air’ can be applied effectively across IELTS contexts through the sample answers given below.

IELTS Speaking Part 1

• Question: Do you often make future plans?
• Sample Answer: “Yes, I do, but I try to keep them realistic. Some of my friends spend a lot of time building castles in the air - dreaming about becoming millionaires overnight or moving abroad without any preparation. Personally, I prefer making practical plans that I can actually achieve rather than just daydreaming.”

IELTS Speaking Part 2

• Cue Card: Describe a time when you had big dreams but could not achieve them.
• Answer Excerpt: “During my school years, I had a dream of becoming an astronaut without studying science. Looking back, it was just castles in the air because I never took the practical steps required to achieve it.”

Castles in the Air Idiom: Practice Exercise

Through the following exercises, you will be able to gain a deeper understanding of the idiom, as well as learn how to use the idiom, 'castles in the air', in the correct context.

1 If someone’s business plan is described as ‘castles in the air’, it means:

A It is well-researched and realistic

B It is creative but impractical

C It is profitable and sustainable

D It has strong financial backing

2 Which situation best illustrates ‘castles in the air’?

A Planning a vacation after saving money

B Completing a project with teamwork

C Buying groceries from a local store

D Expecting to pass an exam without studying 

3 In IELTS Writing Task 2, using ‘castles in the air’ would be most appropriate when:

A Talking about futuristic but unrealistic solutions

B Describing an everyday routine

C Explaining a scientific fact

D Discussing grammar rules

4 Which of the following is closest in meaning to ‘castles in the air’?

A Fool’s paradise

B Foolproof plan

C Down-to-earth idea

D Practical approach

5 The idiom ‘castles in the air’ can have a positive meaning when:

A Used for unrealistic goals

B Encouraging imagination that inspires real action

C Talking about logical conclusions

C Referring to strong foundations

Castles in the Air Idiom: Answer Key for Practice Exercise

1 B

2 D

3 A

4 A

5 B

In conclusion, the idiom ‘castles in the air’ beautifully captures the balance between ambition and reality. While it often refers to impossible dreams, it can also inspire action when used in a positive sense, as seen in literature. By practicing its usage through IELTS Speaking practice tests, examples, comparisons, and exercises, you can confidently integrate it into your communication.

Useful Links:

• Reinvent the Wheel Idiom: Meaning, Origin, Usage & Exercises 
• Live In A Dream World - Idiom of the Day for IELTS Speaking & Writing
• Head in the Clouds - Idiom of the Day for IELTS Speaking & Writing
• IELTS Speaking Vocabulary - 30 Academic Words That Will Help You Score IELTS Band 9 (Part 1)
• Best Books to Increase your English vocabulary
• How to Improve Your Vocabulary Score in IELTS Writing and Speaking?