"Slavery, forced labour, displacement, violent subjugation, racial classification with its humiliating tests, making people think they were inferior because of the colour of their skin, industrialised exploitation — these things are all, and much else besides, the legacy of those systems of repression and exploitation," Maimane said.
"Now there are some people who believe that this was the price of development and infrastructure. Well, if this was the price of development, then I say that this price was too high."
Maimane's comments come on the back of a social media outburst by former DA leader, Helen Zille, who has been hauled before the party's federal legal commission for controversially tweeting that not every aspect of colonialism was bad.
Last week, Zille tweeted: "For those claiming legacy of colonialism was only negative, think of our independent judiciary, transport infrastructure, piped water etc." On Tuesday, Maimane said the country was thinking back to dark days when the people were oppressed and impoverished by the dehumanising system of colonialism, and then apartheid.
Maimane was delivering a speech at a commemoration of Human Rights Day and the Sharpeville Massacre. He was joined by DA Gauteng provincial leader, John Moodey, DA spokesperson on social development, Refiloe Ntsekhe, Tshwane Mayor Solly Msimanga, Johannesburg Mayor Herman Mashaba, and Midvaal Mayor Bongani Baloyi, as well as survivors of the Sharpeville Massacre, and family members of the victims of the Life Esidimeni tragedy.
President Jacob Zuma led the national commemoration of Human Rights Day in King Williams Town, Eastern Cape, where Black Consciousness leader Bantu Steve Biko was honoured posthumously for his role in the struggle against apartheid.
Characterising colonialism further, Maimane also said that development that was forced upon a country under threat of violence was not human progress.
"Development achieved by free exchange with the global community, harnessing the best of human ingenuity and fostering a unity of purpose – that is the development we desire," Maimane said.
"Because, as a party that stands for individual freedom, we can never condone any aspect of oppression. The DA will never stop defending human rights, at home or abroad. Oppression has no place in the world we live in."
Maimane said the DA would continue to build bridges to unite South Africans in a bid to realise late former president Nelson Mandela's dream of a country united around a common South African identity.