A building with a round roof, like the Capitol building in Washington DC or Saint Paul's cathedral in London.
Rotundarotunda
first of all, the building is spelled Capitol, not capital and if I knew the answer I wouldn't have come here.
Right now there is 2...the old one and the new one. Both are located in Springfield.
Domed building rotunda
A domed building where images of stars, planets, and other celestial objects are projected is called a planetarium. These facilities often feature a dome-shaped screen and advanced projection systems to create immersive astronomical experiences for educational and entertainment purposes. Planetariums may also offer shows and presentations about astronomy and space science.
rotunda
A domed hall is a rotunda.
Astrodome in Houston Texas
its domed roof was partially modeled on classical roman building
Taj Mahal
Rotunda