A public execution is a form of capital punishment which "members of the general public may voluntarily attend." This definition excludes the presence of a small number of witnesses randomly selected to assure executive accountability.
While today most countries regard public executions with distaste, in the past they were preferred to executions behind closed doors because they allowed the convicted the opportunity to make a final speech, gave the state the chance to display its power in front of those who fell under its jurisdiction, and granted the public what was considered to be a great spectacle. Public executions also permitted the state to project its superiority over political opponents. Thus, when Charles I of England was beheaded, the reduced height of the block meant that he could not assume the normal kneeling pose, but was forced to lie in a face-down position considered to be especially humiliating.
In Europe and in the northern U.S., the 19th and early 20th centuries saw a shift away from the spectacle of public capital punishment and toward administration of punishment via the deprivation of liberty. While some reformers opposed capital punishment, public executions remained common throughout the 19th and early 20th centuries. Social historians note that beginning in the 20th century in the U.S. and western Europe death in general became increasingly shielded from public view, occurring more and more behind the closed doors of the hospital. Executions were likewise moved behind the walls of the penitentiary. The last formal public executions occurred in 1868 in Britain, in 1936 in the U.S. and in 1939 in France.
Frances Larson wrote in her 2014 book Severed: A History of Heads Lost and Heads Found:
"For as long as there were public executions, there were crowds to see them. In London in the early 19th century, there might have been 5,000 to watch a standard hanging, but crowds of up to 100,000 came to see a famous felon killed. The numbers hardly changed over the years. An estimated 20,000 watched Rainey Bethea hang in 1936, in what turned out to be the last public execution in the U.S."
According to Amnesty International, in 2012 "public executions were known to have been carried out in Iran, North Korea, Saudi Arabia and Somalia." Amnesty International does not include Syria, Afghanistan, and Yemen in their list of public execution countries, but there have been reports of public executions carried out there by state and non-state actors, such as ISIS. Executions which can be classified as public were also carried out in the U.S. states of Florida and Utah as of 1992.