The mosaics, part of a 1,700-year-old town house, were found on the site of a development in Leicester.
Open days attracted thousands of people but a question mark hung over the fate over the most spectacular finds.
Now city mayor Sir Peter Soulsby has confirmed they will form part of a Â£7m revamp of the nearby Jewry Wall museum.
The excavation recovered hundreds of artefacts - including a gruesome carved handle depicting people being fed to lions - but the mosaics were the largest found in the city for 150 years.
Speaking at the final open day on Sunday, archaeologist Jon Coward said: "The big mosaic will be lifted and conserved but quite where it will end up I couldn't tell you but it should be made available.
"One of the things that could happen is it could go in the Jewry Wall Museum or it could go in the foyer of the building on this site, that is up to the developers."
Sir Peter Soulsby said has now said that after discussions with developers and archaeologists, a decision had been made.
"The Jewry Wall Museum is the obvious place for this to go and after 1,700 years beneath our feet they could not have been found at a better time.
"Other mosaics are currently undergoing restoration so this mosaic will join the wonderful artefacts we already have to  make a world class visitor attraction."
It is hoped the refurbished museum will open in two years.

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Wire fell behind to Greg Burke's try but responded through Ryan Atkins and Kevin Brown for a 12-6 half-time lead.
Jay Chapelhow's try and a penalty from Patrick Ah Van gave Widnes a two-point lead after the break.
Matty Russell and Chris Hill went over after Brown's second and third tries, with Ah Van crossing for the Vikings.
England stand-off Brown moved to Warrington for an undisclosed fee at the start of the season after three years at Widnes and was booed by visiting fans throughout, but produced an excellent display for last year's losing finalists.
After a stuttering start to their Super League season, Warrington's win was their fifth straight victory at home and their seventh in a row at the Halliwell Jones Stadium against their neighbours.
They last won the Challenge Cup in 2012, and were losing finalists at Wembley last year when they were beaten 12-10 by Hull FC.
Vikings' injury problems meant they had a number of teenagers in their matchday squad, and Lloyd Roby made his debut.
Denis Betts' side have lost six of their last seven games, and have not won at Warrington since August 2013.
Warrington: Ratchford; Russell, Hughes, Atkins, Lineham; Brown, Patton; Hull, Gidley, Sims, Jullien, Westwood, Cooper.
Replacements: Crosby, Philbin, Smith, G King.
Widnes: Hanbury; Roby, Runciman, Walsh, Ah Van; Mellor, Johnstone; Dudson, Heremaia, Buchanan, Cahill, Olbison, Burke.
Replacements: Manuakafoa, O'Carroll, Walker, J Chapelhow.

Leeds, 15th in the Championship table, looked vulnerable at the start of the season, particularly at set-pieces.
But central defender Bartley has formed an impressive partnership with Pontus Jansson in recent weeks.
Bartley, on loan from Swansea, told BBC Radio Leeds: "You'd have to give the credit to Pep. He had a look and then changed our set-up slightly."
The Yorkshire side were beaten in their opening two league matches of the season, losing 3-0 at QPR and then 2-1 at home to Birmingham.
But on-loan Torino defender Jansson, 25, has played a key role in their improvement.
Leeds have kept clean sheets in their last two games and conceded just two goals in their last four matches - and just one in their last four away games.
Bartley, also 25, explained: "We have Pontus as a spare man who isn't picking up anyone and whose job it is to go and attack the ball, which he has done very well.
"It's made us look a lot more solid. We're going out there now thinking we're going to win, not just hoping."
High-status Roman floors discovered by archaeologists during building work will go on permanent display, it has been confirmed.
[NEXT_CONCEPT]
Kevin Brown's hat-trick against his former club gave Warrington a derby win against Widnes to progress to the last eight of the Challenge Cup.
[NEXT_CONCEPT]
Kyle Bartley believes assistant boss Pep Clotet deserves credit for Leeds United's improved defending.