In AD43 the Roman Emperor Claudius and an army of 40,000 arrived in Britain. Not long after, between AD50-60, the Ninth Legion Hispana were in Lincoln.
Commemorating such a crucial era in the city's heritage, a busy programme of events has been planned for Lindum Colonia Day.
Emma Tatlow, Visit Lincoln partnership manager, said: "It has been 1,600 years since the Romans left the city, yet their marks can still be seen today. We felt it was important to recognise Lincoln's heritage with a designated day and we really hope people will come to visit and take part in the fantastic activities."
Children can excavate a 'skeleton' and use a digital microscope to investigate historic artefacts with Bishop Grosseteste University at St Paul in the Bail.
A Roman camp will be set up in the grounds of Lincoln Castle (Saturday and Sunday) and there will be military patrols through the city and battle demonstrations.
The new, free, digital Roman walking trail will be launched. Using smartphones, it will lead you around the upper Roman city taking in the colonnade, the Roman well and the Church of St Paul in the Bail. It will also tour other Roman landmarks further south, including Roman Lower West Gate and St Mary's Guildhall.
Visitors to St Mark's Shopping Centre will have the chance to try their hand at cleaning finds, examining Roman artefacts and making parts to repair broken objects. The event is being hosted by WHConservation – a partnership between University of Lincoln conservation graduates Leah Warriner-Wood and Terri Dewhurst and conservation students.
More fun will be on offer in The Collection (10am-8pm) where events will include children's craft activities (from 1pm), a Roman talk and demonstration, free afternoon and evening film screenings and Roman life drawing (6pm-8pm).
Entry to the museum is free, but there is a £1 charge for some of the crafts. The day's programme draws to a conclusion with an illustrated look at the development of Roman Lincoln and the hidden city beneath your feet (free, 7pm-8pm).
Paul Mason, site co-ordinator, said: "The Romans had a massive impact on the city, and this is the perfect opportunity to get an insight into life back then.
"We've got a wide range of activities taking place , and we'll all be having a lot of fun."
The Collection has also organised guided tours of Posterngate on Saturday (10am-3.30pm, £1 per person). A rare chance to visit a Roman gateway under the Royal Bank of Scotland, this part of Lincoln's Roman South Wall can be found in a cellar. The wall shows a Roman gate used to access the River Witham.
For full details visit www.visitlincoln.com/romans