The marker at this small memorial site is simple: a cluster of iron shackles that look like they're trying to escape from the surrounding concrete. It commemorates the site of one of the largest slave markets in the US, active most years from the 1830s until 1863. Information panels add context, covering the early history of slave trading within the US – also known as 'internal' slave trading – the work of slave dealers and the ultimate collapse of the industry.