Something fascinating really captures your interest: you can't take your eyes off it or can't wait to learn more about it.
To a sports fan, a basketball game may be fascinating, including the smallest details, like who got the most assists and what kind of defense was played. Music fans find concerts fascinating. Many people think politics is fascinating — they can't get enough TV and magazine stories about the latest political events. Whatever you think is fascinating, it must really hold your attention: you always want to see and know more.