Honolulu, the capital of Hawaii is the closest US state capital to the equator. The closest U. S. territorial capital to the equator is Hagåtña, Guam.
Rome
Tallahassee, FL?
Juneau, Alaska
Annapolis, Maryland, is the state capital closest to Washington, D.C., the capital of the United States.
Rome (Italy) and Vatican City (Vatican City) are the two closest capitals of Europe (even of the world). The distance between them is 0 km. However Vatican city is a sovereign state and not a true capital of a country. The two closest capital cities in Europe are Vienna and Bratislava. Vatican City is a sovereign state and its capital is Vatican City. The state "Vatican City" comprises of more territory than just the capital ( see http://en.wikipedia.org/wiki/Properties_of_the_Holy_See ), so the first statement is still valid.
The closest national capital is Canberra. Canberra. This is the ONLY capital city of Australia. (The next closest capital city is in New Zealand.) :)
Perth is the capital of Western Australia. The closest capital to this city is Adelaide, capital of South Australia.
The closest capital city to Kalgoorlie is Perth, capital of Western Australia.
The closest capital city to Newcastle is Sydney, capital of New South Wales.
The closest capital city to Antarctica is Stanley, capital of the Falkland Islands.
The closest capital city to the Gold Coast in Australia is Brisbane.