Stadia are large, enclosed structures used for sporting events and other entertainment activities. They are also known as ARENAS, which is the term used in the crossword puzzle. Stadia are typically designed to accommodate large crowds of people and often feature seating areas, concession stands, and other amenities. Stadia can be used for a variety of sports, including football, basketball, baseball, hockey, and soccer. Additionally, they can be used for concerts, conventions, and other large events.