So I keep seeing this bad faith argument from racists, but let's address it and then I will go for a nice long bike ride and enjoy the rest of my day - no one is advocating the removal of things built by slaves, we are advocating that you take down statues praising slavers. 
Case in point - the memorial at Auschwitz, which is in Poland. We keep it to remember the victims of genocide. It does not contain any statues of Hitler with big plaques underneath that talk about what a lot of good Hitler did for his local community.
Roman roads were built by the army, not slaves, of course, but it is important to realise that Rome was an Empire built on slavery and also *bad*. Go ahead and like the buildings or whatever but there is no reason to feel fuzzy in your heart for Romans?
The pyramids were not built by slaves, but even if they were no we would not tear them down because keeping monumental works built by slaves helps us commemorate their suffering.
You shouldn't be looking at the Great Wall of China and saying "Wow I guess slavery is alright, then!", you should be asking yourself if ultimately futile public works are worth the suffering and death of thousands of humans. This is basic stuff!!
But of course this is all a red herring. No one has called for anything built by slaves to come down. We have asked for statues that praise the people who owned slaves to come down. This isn't hard. Ask yourself why you need to be told the people who owned slaves were good.
