Sun temple environment, a lost ancient civilisation

Currently a work in progress and in its design stage. I am exploring ideas for an ancient civilisation's sun temple. The end goal is to make a highly detailed real time environment in Unreal Engine 4.

Sun temple interior concept

Sun temple interior concept

I may consider extending the interior to outside just before the entrance to the sun temple.

I may consider extending the interior to outside just before the entrance to the sun temple.

Sun Temple interior concept 2

Sun Temple interior concept 2