The kicker? Heroin was synthesized by Felix Hofmann, the same guy Bayer says invented aspirin.
It used to be totally cool for kids to take it (but they really shouldn't, ever)
Back in the old days, kids were given aspirin on the regular. However, a connection was made between kids taking aspirin for chicken pox or influenza and a serious condition called Reye syndrome, which can result in seizures, brain swelling, brain damage, or coma -- and that's just part of the constellation of troubles that strike kids who are affected. There's no cure for the condition (only supportive treatment), so experts advise that parents abstain from giving their kids aspirin unless they're being carefully monitored by a physician.
No one was sure exactly how it worked until the '70s
And for figuring it out (it inhibits prostaglandine synthesis, duh), John Vane won the Nobel Prize in Medicine. Those were simpler times, when we didn't need to know how a drug worked -- just that it worked. Of course, that line of thinking also led to stuff like Reye syndrome, so chalk one up for progress.
It may have benefits we don't even know about yet
Despite being well over 100 years old, aspirin is still actively involved in studies, clinical trials and research. Recent studies have shown that daily aspirin use may reduce a person's chances of developing certain cancers by 20%, but research is still ongoing, with clinical trials open at this very moment, in the hopes that scientists can get more insight and data to develop a clearer picture.