How would i say "of monuments" in french?

do i say: "de monuments" or "de les monuments," or furthermore, what about "des monuments" ?

now, what if i want to say "of some of the monuments" would i say "de des monuments" ?

I think it'll make more sense to say  

J'achèterais des souvenirs de quelques monuments

Des monuments the other one is quelque monument

answer:

where is the musée d'orsay? to lyon in paris in the suburbs 2. what was it originally? it was a station. it was a theater. it was a museum. 3. in what year is the building inaugurated? in 1939 in 1900 in 1986 4. who was his architect? orsay orson welles victor laloux 5. in what year is the building transformed into a museum? in 1986 in 1900 in 1939 6. in which art is the museum mainly dedicated? to nineteenth-century art to impressionist art to twentieth-century art