The Ancient Church stands broken down between massive skyscrapers in Stem City. The structure is built out of a fine black marble. A barbed wire fence protects its perimeter. The doors are always locked. The only way to enter is through the shattered windows.
The cathedral above is relatively small. The majority of the church is comprised of underground tunnels. Catacombs filled with coffins of forgone Stems members line the walls. Doors down there seem to open, close, lock and unlock at random intervals. Devoid dining halls, empty barracks, and praying chambers all periodically appear in the maze-like corridors. The Grand Shroom's stems run in and out of the catacombs.
The only one taking care of the building is the mysterious Unnun. There was once an urban legend that if one was to enter the church and lock eyes with the caretaker, they wouldn't return.
When the time comes, the undead nun will call out to the next in line to claim Stem City's rulership role. They will go through a vigorous, years long process of learning the truth about Stem City and its history before being erected to the highest position of power.
First built by the cult of Stems long before Stem City's founding, it was built to worship the Grand Shroom. The beast known as Stem Origin was frequently fed by Sister Concordia.
After the Council of 12 was formed and the Stems village was colonized by more than original Stems tribe blood, the church fell into disrepair as the true Stems religion became frowned upon. However, loyalists remained and fixed the church as best they could. Secret worshipping chambers and vast barracks came to be dug out underneath the small church by the zealous members. The twisting tunnels followed alongside several underground Grand Shroom stems.
Throughout the Volva Tribe Burning conspiracy up until Ahsonov's takeover, the church was kept clean by its small remaining numbers. However, the secret society's tunnels below were converted into winding catacombs as Unnun and Count Ahsonov betrayed the remaining Stem's Origins cultists in an attempt to cover up their coup of the Council of 12.