Friday marks the official departure date for the UK to begin leaving the EU and the start of a transitional period allowing businesses and government to prepare to post-Brexit arrangements.
It will also mark the start of negotiations over trade with the EU.
The Union Flag was set to be flying in Wolverhampton today, after the city's council leader backed the proposals at a meeting earlier this week.
Conservatives in the city called on the Labour-run authority to raise the flag outside the Civic Centre to signal the UK's exit from the EU.
The proposal, put forward by Councillor Simon Bennett, was initially branded a "political stunt" – but was then backed by leader Councillor Ian Brookfield.
The council leader called for people to unite, put the politics behind them and mark the day with dignity.
Councillor Brookfield said: "I raise to second this particular motion. Let's take some of the politics out of it – perhaps people on my side get demonised when we talk about national and international events. But my side are all Wulfrunians – all British, bus drivers, nurses, teachers, shop workers, students.
"These are the people on Wolverhampton – these are people plucked from the areas in Wolverhampton. Why would they not be proud to fly the flag on such a day?
"It's a significant moment in our country's history. People have fond memories and some people will not and we accept that because we're democrats – we abide by what people say."
Councillor Simon Bennett said: "This is a significant moment where we will begin a new chapter. The past three-and-a-half years have been incredibly divisive – 63 per cent of people in this city voted to Leave and the idea to get Brexit done resonated with voters at the election.
"It's an opportunity to heal those divisions and get back to those everyday issues. It's about bringing people together for this moment and then move on. The flag is a symbol of democracy, of hope and freedom."
Stafford Council will fly also the Union Flag from the roof of the Civic Centre, in Riverside, today.
Councillor Patrick Farrington, Stafford Borough Council leader, said: "Today we will be flying the Union flag from the Civic Centre to mark an important occasion in this country’s history when Britain leaves the European Union.
"And I have also asked for the European Union flag, which is currently flying outside Victoria Park, to be removed.”
As Dudley Council flies the Union Flag all year round, the authority will instead light their Priory Road Council House up in the colours of red, white and blue to mark the day.
The three windows above the front door will be lit up in the colours of the national flag from 6pm ahead of the country officially leaving the European Union at 11pm.
Council leader Patrick Harley said: "Today is a historic day for Britain, and it is important we mark that.
“The country has been through an unprecendented time of uncertainty in recent years. But now it is time to move on, whilst continuing to recognise the importance for us to build on our relationships with our international trade partners.
“It is an exciting time for Dudley borough with several multi-million pound investments in the pipeline, and we are looking forward positively to cracking on and making our plans a reality.”
While, Walsall Council and Sandwell Council fly the Union Flag outside their council houses at all times and will continue to do so today.