The execution of H.H. Holmes, one of America's first well-documented serial killers, remains a significant event in criminal history. Born Herman Webster Mudgett, Holmes was executed on May 7, 1896, in Philadelphia, Pennsylvania. His life and crimes have been the subject of extensive investigation and speculation, particularly regarding the infamous "Murder Castle" he constructed in Chicago. This building was allegedly equipped with secret passages, trapdoors, and a kiln to cremate bodies, though some aspects of these tales have been considered exaggerated over time.

Holmes was a master manipulator who engaged in various fraudulent schemes, including insurance fraud, and is believed to have killed numerous individuals, primarily to steal their property. His victims often included employees, who were required to take out life insurance policies naming Holmes as the beneficiary, and women he became engaged to before killing them after gaining control of their savings. The true number of his victims remains uncertain, with Holmes himself confessing to 27 killings, although only nine could be confirmed. Some estimates suggest he might have killed up to 200 people, but these numbers are speculative and often considered part of the lore that surrounds him.

Following his arrest for insurance fraud, Holmes' criminal activities began to unravel, leading to his trial and eventual execution. At the time of his execution, it was requested that his body be buried in concrete, purportedly to prevent grave robbers from desecrating his body, a practice Holmes himself had engaged in during his lifetime.

Holmes' life story, including his execution, has been the subject of various articles and books, shedding light on his psychological profile and modus operandi. Despite the years, interest in Holmes and his crimes continues, illustrating the enduring fascination with one of America's first serial killers and the macabre details of his reign of terror​