Newbie with modelling problems

Hello everyone!
I’m making a tower for a caste and need to do a rounded balcony so I extruded a few faces and well… I’m stuck.
Here’s the image:

The selected area is a tileable segment wich I need to repeat all arround that surface… but I have no idea on how to do it.
I tried using spin but i can’t make it fit exactly, duplicating and rotating doesn’t work either.
¿Any ideas?

Thanx a lot for your time!

did you try spin dup? (with cursor in cetner of balcony) - just figure out exactly how many arches you need (since they are extruded from the original balcony mesh, this should be simple to calculate.) and remember to remove doubles when done.

Yeah, spin dup is the tool. Just remember to remove all the edges on the sides so that you don’t have faces on the inside later

Did it! Thank you so much!