A monolithic temple structure

What the white stranger called the Nexus was inside a monolithic temple structure, built at the side of a smooth looking mountain, and so far appeared to have only one room, the hall with the gate device, that looked identical to the one they had found on Itheamh.

Temple like structure found near the equator of a planet in orbit around star Rohardoor and located in the Sculptor Galaxy. The planet was home to an advanced species that seemed to have contact with the Pree.