I wrote the same. I teach ESL and using the simple present here doesnt make much sense since it isn't something regular and build is also action word. Although if translated from korean it isnt the present continuous so I understand why I got it marked wrong.
Could 여기에서 work? From my understanding 에 is for simple static locations, but here it's being specific about the action at the location so wouldn't 여기에서 be correct? I still have problems with these two particles ;;