Inco Superstack

The Inco Superstack in Sudbury, Ontario, with a height of 381 metres (1,250 ft), is the tallest chimney in Canada and in the Western Hemisphere and the second-tallest freestanding chimney in the world, after the Ekibastuz GRES-2 Power Station, in Kazakhstan. It is also the second-tallest freestanding structure of any type in Canada, behind the CN Tower but ahead of First Canadian Place. As of 2023, it is the 51st-tallest freestanding structure in the world. The Superstack has a tapered shape as it gets wider near the base reaching a width of 35 meters. It is located on top of the largest nickel smelting operation in the world at Vale's Copper Cliff processing facility in the city of Greater Sudbury. In 2018, Vale announced that the stack would be decommissioned and dismantled, beginning in 2020. Two new, smaller stacks were constructed under the company's Clean Atmospheric Emissions Reduction Project. In July 2020, Vale announced that the Superstack had been officially taken out of service but would remain operational in standby mode for two more months as a backup in the event of a malfunction in the new system, and that the dismantling of the Superstack would then begin. Although some have called for the stack to be left in place as a tourist attraction, in September 2024, Vale announced an updated plan, which will see the stack dismantled by 2029. Dismantling of the Superstack commenced in September 2025 and as of October 2025 the stack height was reduced by about 35 meters, giving it a current height of approximately ~345 meters. The current height reduction resulted in the Superstack falling from second to eighth place for the tallest chimney in the world. Demolition work is set to begin in May 2026. In addition to further reducing sulphur dioxide emissions by...