Visualisations are a key tool for the Digital Panopticon project, which is linking together a vast range of digital records about the 90,000 people who were convicted at the Old Bailey in London between 1780 and 1865, and subsequently imprisoned in England or transported to Australia. The project is using visualisations for two purposes: to better understand our core datasets, and to summarise our findings. The first has allowed us both to identify errors and limitations in the underlying data, and to see overall patterns. The second is more challenging: in order to map convict journeys we need to summarise relationships between datasets and the variety of life events they record, both criminal (trials, punishments, convictions and reconvictions) and personal (dates of birth, marriage and death; places of residence, family circumstances and occupations in census records), and involving tens of thousands of people. This paper will discuss our choice of visualisation tools, assessing their suitability for summarising key information and allowing web-based manipulation by users, and then present some preliminary visualisations of our data. First, we will demonstrate how visualisations have helped us see distortions in individual datasets, such as ‘age heaping’. Second, we will examine the results of our ongoing record linkage activities by focusing on the relationship between the judicial sentences recorded in court records and the actual penal outcomes found in the records of executions, transportation and imprisonment. Third, we will discuss our strategies for using visualisations to summarise individual convict lives. Finally, we will reflect on the strengths and limitations of visualisations as tools for understanding and analysing large volumes of historical data.