I am a stadium known for my unique, asymmetrical design, and the unusual shape of my roof. I've hosted multiple major sporting events, but the specific architectural features make me hard to forget. What am I?

1. My design was inspired by the shape of a clam shell.
2. I am located in a major city in the United States.
3. My seating bowl wraps around the field in a crescent shape.
4. I have been home to both a major league baseball team and a major league football team.