Semicircular building recess Crossword Clue

 The answer to the crossword clue "semicircular building recess" is APSE. It is a 4-letter word that can be used as a crossword clue. 

Apse is a semicircular recess at the east end of a church, typically containing the altar. It is often vaulted and decorated with mosaics or other religious art. Apses can also be found in other buildings, such as mosques and synagogues.

In the context of the crossword clue, "semicircular building recess", the answer is apse because it is a word that is associated with a semicircular recess in a building. It is also a relatively short word, making it a good fit for a crossword clue.