"The church hall was small and it was 21 meters long and 11 meters wide. For extension it had apse ending with semi-circle."

Hallo aus Quedlinburg!

I am an American teaching university students (Texas Tech U. in Lubbock, TX.) beginning German and running a Center for TTU here in Quedlinburg. The two English sentences you offer really interest me because they seem to be so poorly constructed, almost as if they were a translation from some other language, perhaps even from German? For example: ...it had an apse (understood to always be a semi-circle?).

It would be great to have a native German speaker weigh in on this architectural description, because I often need to explain just such things here in Quedlinburg to my students. As you see above I gave it a try. The first sentence might be something like: Das kleine Kirchenschiff (Die kleine Kirchenhalle? )war nur 21 Meter lang und 11 Meter breit. Als Verlängerung gab es eine Apse( im Halbkreis).

"The church hall was small and it was 21 meters long and 11 meters wide. For extension it had apse ending with semi-circle."

Sorry,

Just as I sent my suggestion I realized two errors: Apse instead of Apsis and really no need for the half-circle addition.

What do you think?

...und wurde durch eine (halbrunde) Apsis verlängert

ich meine, eine Apsis ist meistens halbrund, deswegen braucht man das hier vielleicht nicht nochmal zu erwähnen

oder:

...und wurde um eine (halbrunde) Apsis erweitert