parliament building; National Diet Building (Japan); Capitol (US); Houses of Parliament (UK)
Refers to the physical building housing a national legislature. In Japanese contexts, it specifically means the National Diet Building in Tokyo. Can also be used for foreign equivalents like the US Capitol or UK Houses of Parliament when context makes the country clear.
The National Diet Building is in Nagatacho, Tokyo.
I toured the Capitol in Washington, D.C.
We toured the National Diet Building on our school trip.