Four postboxes have been painted black to honour black Britons including Sir Lenny Henry and nursing pioneer Mary Seacole.
The Royal Mail postboxes - in London, Glasgow, Cardiff and Belfast - have been painted as part of Black History Month in October.
Each features a significant figure in the British black community and has a social media link.
Royal Mail says the aim is to help mark the success of black Britons.
A QR code on the postboxes can also be scanned to bring up a list of the black Britons who have appeared on special stamps.
The London postbox is in Acre Lane, Brixton, near to Black Cultural Archives.
It features the image "Queuing at the RA" by Yinka Shonibare, one of six artists who was commissioned by Royal Mail to produce original artworks for a set of special stamps issued to mark the 250th anniversary of the Royal Academy (RA).
"As a citizen of the Commonwealth, it was particularly important to me to be making a visible contribution in a historic public space," Mr Shonibare said.
Footballer Walter Tull, who became the first black player to sign for Rangers (before he was killed in 1918), appears on the Glasgow postbox in Byres Road. He had played as a forward with Spurs and Northampton Town.
He featured in a set of stamps released in 2018 to mark the centenary of the end of World War One and was also the first black Army officer to command troops in a regular unit.
Mary Seacole, a Jamaican-born nurse who cared for wounded British soldiers during the Crimean War, features on the Cardiff postbox in King Edward VII Avenue.
And Sir Lenny Henry, a stand-up comedian, actor, singer, writer and television presenter and co-founder of the Comic Relief charity, is honoured by the postbox in Bedford Street, Belfast.
Peter De Norville, Royal Mail's head of diversity and inclusion, said: "Black History Month is a great opportunity to celebrate the contributions that black people have made to this country over many generations.
"We are also using it as an opportunity to celebrate the vital work that our black employees do throughout the nation, from the mail bag to the meeting room."