[Tdol]

This is an area that is a real mess.
We use 'the' with European mountains that take a definite article in their language.

It seems that we often use a definite article if a word like 'rue' comes at the beginning, but there are many contradictions when we use foreign words.

You'll see both the Medici and the Medicis.

I honestly have no idea about art masterpieces- we say the Mona Lisa, but Guernica.