New Delhi, Jan. 15 -- Nadia Comaneci, Apolo Ohno, Bart Conner and Cullen Jones were among the more than 300 Olympic and Paralympic athletes who gathered Tuesday under the peristyle at the Los Angeles Memorial Coliseum, where the Summer Games will open in 2028.

In an effort to promote Wednesday's registration launch for tickets to the Los Angeles Games, the athletes representing 28 different Olympics dating to 1960 joined Janet Evans in a short countdown to the lighting of the Olympic Cauldron against a clear blue winter sky.

"LA is committed to delivering an athlete-centered games and that can only happen if athletes are actually at the center of our planning," said Evans, the Olympic champion swimmer who is chief athlete officer for th...