I was interested to see your Flashback article about the Rock Gardens Assembly Hall. This was opened in 1860 and covered almost 10 acres, and the hall was accessed by a concealed stone spiral staircase concealed within the cliff face, leading from the domed Moorish temple on Rutland Terrace. The staircase remains to this day.
There is a bricked-up exit in the lower cliff face. Many years ago some bricks were missing, and the staircase was accessible by small boys like me who could climb through the hole and stand on the stone steps.
At the first evening entertainment 2,000 people were present.