Sharks Patrol These Waters:Kara Walker's Fons Americanus.

"Once you open up the Pandora's Box of race and gender ... you're never done" - Kara Walker.

I wouldn't say that Kara Walker, who's been given the latest Turbine Hall installation at Tate Modern, likes it the way. More that she accepts it IS that way - so she goes ahead and works with it.

Most work I'd seen of hers in the past had made use, primarily, of shadow puppets and had been affecting, powerful, and quite different to much other art. I'd also seen, slightly less memorably I must admit, a pencil and collage work of hers in Victoria Miro's 2016 show - Protest. But, for the Tate, Walker's gone large. Really large. It's a space that almost demands it. You only have to look at previous commissions by Anish Kapoor, Olafur Eliasson, Miroslaw Balka, Carsten Holler, and the first one ever from Louis Bourgeois to see that.

When I visited Soul of a Nation:Art in the Age of Black Power with my friends Mark and Natalie in October 2017 I remarked on how influential that show had been, how many people of colour it had brought in, and how the Tate would do very well to try and keep that audience on board, London is after all a very multicultural city, by hosting more shows that look further afield than the hegemonic, mostly white, mostly male, mostly European or American, consensus.

Which, to be fair to them, they've done. Apprpaching Walker's Fons Americanus, you're first greeted by what appears to be a large ceramic oyster. Peering out of it - not a pearl - but a small model of a person. A crying boy filling the shell with his tears. This is merely an aperitif to the rich visual feast Walker will soon serve us.

It's something of an outlier but not a huge one. It fits with the overall aesthetic and with Walker's claim that her "work has always been a time machine looking backwards across decades to arrive at some understanding" of her "place in the contemporary moment". Fons Americanus is a sculpture in the form of a fountain that seeks to ask questions about how public statuary affects how we view our own history while also serving to give us an oblique narrative on the African diaspora.

Or, to put it less tactfully, the slave trade. The role of monuments in American life has been a very hot topic in America recently. The Unite the Right rally in Charlottesville that saw swastikas and burning torches on the streets of Virginia and resulted in the death of counter protestor Heather Heyer in a far right terrorist action was, nominally, inspired by that city's decision to remove a statue of Confederate States Army commander Robert E.Lee from a local park.

Closer to home, the statue of slave trader and philanthropist (there's a twin job description that doesn't sit right) Edward Colston in Bristol is regularly protested and even vandalised. Undoubtedly there are many statues, in many countries, of bad men (and it is mostly men). Or of men who are bad by our modern standards. Or of men who were mostly good but did bad things.

That doesn't necessarily mean we should tear them all down but it certainly means we should have a conversation about them. It should definitely mean that they're balanced by having memorials (and they don't have to be statues, there's something very Victorian and patrician about statues, much as I almost always stop to look at them and read them) to not just colonial powers, army commanders, and war heroes but to thinkers, artists, poets, and rebels who fought against injustices even when those injustices were being carried out by authority figures or governments.

Fons Americanus is at first glance an impressive construction. It continues to be so. The scale and design looked a little familiar but it wasn't until I read that it was based on the Victoria Memorial that stands at the end of The Mall in front of Buckingham Palace that it hit home where I'd seen it before.

Or, in fact, something quite unlike it. The Victoria Memorial was designed and sculpted by Sir Thomas Brock in 1901 and unveiled a decade later as a memorial to the titular monarch who was a figurehead of Empire. Fons Americanus is anything but a celebration of Empire or, indeed, empires. It looks at the interconnected histories of Africa, America, and Europe and the water that spouts from the breasts of a female figure that tops the fountain and the water that surrounds the sculpture represents the Atlantic Ocean that so many enslaved people drowned in during transit between those three continents.

A circular walk around the base of the fountain will reveal to the eager eye, or (like me) those who have read about it beforehand, references to JMW Turner's 1840 painting Slave Ship, Winslow Homer's 1899 Gulf Stream (a work fellow African-American Kehinde Wiley subverted in his In Search of the Miraculous show at the Stephen Friedman Gallery last year), and even Damien Hirst's The Physical Impossibility of Death in the Mind of Someone Living from 1991. You know, the dead shark one.

Elsewhere, the Roman goddess Venus puts in an appearance atop a shell, there's a grotto, and there's a crying boy. Venus is reimagined as a "priestess from Afro-Brazilian and Caribbean religions" and is intended to represent joy, celebration, and liberation. Big butts are venerated too but it's not all so positive. The sharks that patrol those waters are eagerly awaiting their potential prey.

By inverting the narrative of Empire and showing who really built it, the African slaves far more than the slave traders or the monarchs who oversaw the whole wretched business, Walker has created a work that's both educational and entertaining. You're not allowed to splash in the fountain but you are allowed to sit on its edge and from there you can either ponder the wit, wisdom, and power of her art or your could just enjoy the spectacle of the thing.

Ideally you'd do both. Kara Walker has signed off her work, you can see a large 'mocked up to look old' sign on a nearby wall, with the name Kara E Walker NYT. NYT stands for Not Titled Yet, a dig at the honours system. She's right to have a dig at that system and why would anyone want to be knighted or even recognised by a hierarchy built on such cruelty and division?

The people I tip my imaginary titfer to are the likes of David Bowie, Stephen Hawking, Aldous Huxley, Frank Auerbach, Graham Greene, E.M.Forster, Danny Boyle, Michael Faraday, David Hockney, Peter Tatchell, and Harold Pinter who recognised that the offer, and acceptance, of a knighthood served only to prop up a rotten old system and to make themselves sound fancier. Obviously not everyone who accepts a knighthood is bad for doing so but I'm #justsaying that Jimmy Savile and Philip Green were both offered, and accepted, the title Sir.

More than that honourable list of refuseniks though the people this monument really represents are the people whose names were lost to history, those who were never given so much as an opportunity to make history even as they helped created empires and status for their 'masters'. The long name that Walker has given the work (you can read it below) and her NYT quip are, possibly, the only two false moves in an ensemble that works on several different levels and, at a time when extreme right wing forces are taking control of the narrative and distorting historical truths to further their own pernicious agenda, it couldn't be more relevant. Thanks to Tate Modern for making this work free, and available, to all and thanks to Kara Walker for having the forethought and perception to create a piece that starts off as fun and ends up having you question even your own ideas of how history is created and whether the stories we choose to tell us each other about it are even true or not.