I dry map showing a monumental structure (7)

I believe the answer is:

pyramid

I'm a little stuck... Click here to teach me more about this clue!

'structure' is the definition.
(pyramid is a kind of structure)

'i dry map showing a monumental' is the wordplay.
'i dry map' can be anagrammed to 'PYRAMID'.
However, I'm not clear how this is indicated.

Can you help me to learn more?

(Other definitions for pyramid that I've seen before include "Ancient Egyptian building" , "something ancient in the sand?" , "old monument" , "hierarchical organisation" , "old tomb" .)

I've seen this clue in the Sydney Morning Herald.

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