raltca lujvo

x1 is a/the capital of x2.

Cf. ralju, tcadu. More general than trutca. May be the financial (e.g. New York in USA), industrial (e.g. Sao Paulo in Brazil) or religious (e.g. Mecca in Saudi Arabia) capital of its polity but not necessarily the seat of government.

In notes:

tc1=tu1 is the administrative capital (seat of government) of tu2=tc3 located in tc3