# S3 | anthropic/claude-opus-5 | run 1

## Prompt

What is the capital of Australia?

## Response

The capital of Australia is **Canberra**, located in the Australian Capital Territory (ACT) in the southeast of the country. It was purpose-built as the national capital and has held that role since 1913, when construction of the city began.

## Why Canberra and Not Sydney or Melbourne

Canberra was chosen as a compromise after Australia's federation in 1901, when Sydney and Melbourne both claimed the honor. The constitution required the capital to sit in New South Wales but at least 100 miles from Sydney, and Melbourne served as the interim seat of government until Parliament moved to Canberra in 1927.

## Key Facts

| Attribute | Detail |
| --- | --- |
| Population | Roughly 470,000 (metropolitan area) |
| Territory | Australian Capital Territory |
| Design | Planned by American architects Walter Burley Griffin and Marion Mahony Griffin |
| Notable institutions | Parliament House, High Court of Australia, Australian War Memorial, National Gallery of Australia |
| Largest Australian city | Sydney (not the capital) |

A common misconception is that Sydney is the capital, since it is the country's largest and best-known city. Melbourne is the second largest, while Canberra ranks around eighth by population.

Would you like details on Canberra's main attractions or how its planned layout compares to other purpose-built capitals like Brasília and Washington, D.C.?
