De or het modemuseum?

The correct Dutch article is:

het modemuseum

Rule Words ending in -um and -ium: usually het. See the rule

How to use modemuseum

the modemuseumhet modemuseum
this modemuseumdit modemuseum
that modemuseumdat modemuseum
our modemuseumons modemuseum
your modemuseumjouw modemuseum
every modemuseumelk modemuseum
which modemuseum?welk modemuseum?
a big modemuseum / the big modemuseumeen groot modemuseum, het grote modemuseum