For the better part of five centuries imperial colonialism by Western European powers did immeasurably significant damage to so many parts of the world, the Americas in particular. The Age of Discovery morphed into the rape and pillage of new territories discovered, with ruling powers being motivated by greed, egotism, and then outright genocidal bigotry. One could argue age of imperial colonialism initiated what has turned into accelerated and seemingly irreparable harm to this planet, leading to the ecological crises we face today. That's what's been left behind by those so-called empires.
The Spanish Empire was one of the first to settle in the new world, being funded by a powerful crown. At its peak, Imperial Spain held the most territory in the Americas, spanning south from Tierra del Fuego as far north as modern day California. Spain also had a very powerful Catholic Church backing its colonial aspirations from the very beginning, weaponizing religion to secure its grip on the region and exploit its resources and peoples behind the guise of divine superiority. Colonialists brought with them numerous diseases, leading to widespread epidemics across Central and South America. Over 50 million died in the century following Columbus' discovery of the Americas, due to disease, slavery, and outright slaughter - it's been labelled as the great dying. It even caused a global climate event where the planet briefly cooled. The long-term effects of those atrocities can be seen to this day in terms of religion, language, and many other sociopolitical aspects.
But I digress. I think there's a case to be made when it comes to the worst empire of all time that Imperial Spain and the British Empire are neck and neck for first place, leaving behind a disgusting legacy. It could be a coin flip but that hardly matters; both could hold that disgraceful title.
For us here in Canada, however, it's predominantly the British Empire's legacy. And there should be no statues commemorating any of it.