The most common and most likely answer to this crossword clue is the 9 letter word CENOTAPHS
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Buddy explains!
The straight part
We know that "monuments" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case monuments = cenotaphs.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does CENOTAPHS mean?
CENOTAPHS noun- A monument, especially in the form of an empty tomb, erected to honour the dead whose bodies lie elsewhere; especially members of the armed forces who died in battle.