created a group of offenders that would start slowly but steadily filling up the country’s criminal justice institutions. Hiding and obscuring migration Very little is known about administrative detention practices during this time but it can be safely said that administrative detention of aliens was limited to small numbers. However, this is by no means a period of no significance to the development of the detention estate. By 1999, there were 550 foreign nationals detained in police establishments in the region of Attica alone. What is more, foreign nationals accounted for 47 per cent of the total prison population (CPT, 2001c), demonstrating from very early on how the architecture of legislation and the institutions of criminal justice and border control conspired and coalesced to exclude some people in the country, as has been shown in other contexts (Bosworth, 2019; Aas, 2020). Therefore, while detention was not the main aim of immigration policy during 1990-2000, immigrants were confined in various low-visibility spaces across Greece. The duration, the place and the conditions of detention are not specified in the 1991 legislation. As a result, detention operated in a default state of secrecy and was rarely subject to external monitoring. There were, likewise, few independent organisations which would deal with issues faced by immigrants, let alone support those in detention. The Greek Ombudsman, for example, was founded in 1998. One of the few sources of information during this first phase of detention is the reports of the European Committee for the Prevention of Torture (CPT) that visited and monitored conditions throughout Greece. The CPT made three visits during the period of 1990-2000, two periodic in 1993 and 1997, and an ad hoc one in 1999 ‘required by the circumstances’ due to disquieting findings concerning the conditions under which foreign nationals were being held during the first two visits and the inadequate nature of follow-up reports by the Ministry of Public Order.42 Until 1993, there were no specific establishments for the detention of aliens. Instead, foreign nationals were held for extended periods of time in police stations, sometimes for 42 It also made an ad hoc visit in 1996 but it only concerned a mental health institution (CPT, 2001a). 71