Complex sentence: It was called the world's largest theatre by its builders and had a seating capacity of 6,000, a 100x200ft (30x61m) stage and had state of the art in theatrical technology, including a rising glass water tank.
Split into simpler sentences: It was called the world's largest theatre by its builders and had a seating capacity of 6,000, with a 100x200ft (30x61m) stage. The theatre housed state of the art theatrical technology, including a rising glass water tank.