The assault on the home-run record is all the more remarkable when one considers that it was once thought unbreakable. Onion Sports looks at sports milestones that in all likelihood will stand forever:

Ty Cobb's .366 career batting average: Cobb's amazing feat was accomplished mostly through sheer racism; racism abolished from baseball in 1947

Cy Young's 511 wins: This record holds the all-time record for being on the most "unbreakable records" lists

Wilt Chamberlain's 100-point game:  Will never be broken because today's NBA stars are team-oriented players who are not interested in selfishly accumulating individual accomplishments

Mickey Mantle's 600-foot homerun: No steroid can match the strength of whiskey

Carl Lewis' gold medal in 1984 Olympics 100-meter dash: Olympic officials confirm this event has been over for more than 20 years

Amateur golfer Jack Gosch's two holes-in-one on two consecutive shots: Though Tiger Woods has come close, no one has ever gotten two holes-in-one on a single shot

Richard Petty's 200 career racing wins: No driver has come close to Petty's record since NASCAR implemented "rules" in 1995

Johnny Unitas' 47 consecutive games with a touchdown pass: Secret to passing accuracy contained in flattop haircut; today's players unwilling to make that ultimate sacrifice

Cal Ripken Jr.'s 2,632 consecutive games played: No other player will ever have the desire to show up to the ballpark that often