original: The centrepiece is Cathedral Cave with the massive Altar Rock.
simplifications: The centrepiece is Cathedral Cave with the huge Altar Rock. Cathedral Cave with big Altar Rock is in the center. Cathedral Cave is the centerpiece with the Altar Rock. The centrepiece is Cathedral Cave. It features the massive Altar Rock. The centrepiece is Cathedral Cave. It has the massive Altar Rock. The centrepiece is a Cathedral Cave with a large Altar Rock. In the center is Cathedral Cave with the massive Altar Rock. The focal point is the giant Altar Rock at the Cathedral Cave. The centerpiece was the Cathedral Cave with a massive altar rock. The main feature is the Cathedral Cave with the big Altar Rock.