Strange thing though about that roof -- it won't be used tomorrow when Wales host England in the latest round of the Six Nations. That's the latest report because both teams have to agree and England want the ground open to whatever weather hits the city.
Maybe they will change their minds if the weather forecast is dirty or perhaps it's another double-bluff from Eddie Jones who remains unbeaten in his latest coaching role with England.
Even if the roof stays open, the wall of sound is bound to be thunderous and will threaten to reach deafening levels if Wales can find a way to derail the defending tournament champions.
They tried a few early gimmicks this week with the BBC having to pull one trailer which had fans rendered speechless when asked what was good about England.
In the match-ups there is much to admire about England but it looked that way before their opening round against France and proved to be baseless. They scraped through with a win at Twickenham but were ponderously uncertain.
Wales took their talents to Rome where they started slowly but after the arrival of nippy replacement five eighths Sam Davies got their game together and spanked Italy.
That sparked many to call for Davies to start this week ahead of the recovered senior playmaker Dan Biggar, a move coach-turned-columnist Clive Woodward thought would better assist his side's backline attacking power.
Maybe Woodward was serious but Wales coach Rob Howley has stayed with the game management of his senior man.
The other area where Wales will give themselves an advantage is having the twin loose forward strike force of Justin Tipuric and former skipper Sam Warburton to make life uncomfortable for the less experienced England flankers.
The visitors can call on the experienced flanker James Haskell to give some momentum from the bench while Wales can counter with Talupe Faletau in their reserves.
Maybe it will come down to a Leigh Halfpenny-Owen Farrell goalkicking contest but there's no question, the stakes have gone up a notch for this annual grudge match.