This paper attempts to set out what is known about the places in the city of Rome used for detention and execution. It is not based on personal inspection of the sites, but only on the ancient evidence and modern discussion, and simply aims to meet the absence of a full up-to-date account in English of the history, location, character and function of these places, viz. the carcer, lautumiae, Saxum Tarpeium, Scalae Gemoniae, and the elusive robur. It does not deal with the wider question of what crimes merited the death penalty or called for its infliction in this or that manner, nor, apart from a few items, is it carried beyond the Julio-Claudian dynasty.