This one is easy.

A capitol is a building housing a seat of government. That’s all.

Any other meaning you might intend uses the word capital, which has many definitions:

• The most important city or town of a country or region, usually its seat of government and administrative center
• A place associated more than any other with a specified activity or product
  • – Milan is the fashion capital of the world
• Wealth in the form of money or other assets owned by a person or organization or available or contributed for a particular purpose such as starting a company or investing
  • – the senior partner would provide the initial capital
  • – rates of return on invested capital were high
• The excess of a company’s assets over its liabilities
• People who possess wealth and use it to control a society’s economic activity, considered collectively
  • – a conflict of interest between capital and labor
• A valuable resource of a particular kind
  • – there is insufficient investment in human capital
• A letter of the size and form used to begin sentences and names
  • – he wrote the name in capitals

Photo credit: ‘Capitol in Austin Texas at Night’ by Eric Hunt (Own work) [GFDL, CC-BY-SA-3.0 or CC-BY-2.5], via Wikimedia Commons.