The most common and most likely answer to this crossword clue is the 7 letter word FOLLIES
I've seen this crossword clue in Independent
F
O
L
L
I
E
S
Buddy explains!

The straight part
We know that "curious buildings" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case curious buildings = follies.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 FOLLIES mean?
FOLLIES noun- Foolishness.
- Thoughtless action resulting in tragic consequence.
- A fanciful building built for purely ornamental reasons.