"Danh lam thắng cảnh"
名覽勝景. A number of SIno-Vietnamese words have had their initials change from /m/ to /j/ like 名 and 民 because the Middle Chinese /mj/ initial lost the /m/ leaving behind just the /j/ (y sound) in Middle Vietnamese. So mdanh > danh and mdân > dân.
It's actually 名藍勝景. 覽 => lãm, which is an understandable guess. As glossed in Duolingo, danh lam carries a meaning of famous pagoda.
Thanks for the correction. As an added note: it appears that 藍 shares a common etymology with the Vietnamese chàm (indigo). 藍 (Old Chinese: ɡ·raːm > Middle Chinese: lɑm). Proto-Vietic: ɟaːm > Vietnamese: chàm.
lam (藍) is an abbreviation of già lam (伽藍), which is borrowed from Sanskrit, means Buddhist temple.