Downtown Markham is the main downtown of Markham, Ontario, Canada. Currently under development, it is located within Markham Centre near the historic Unionville district and is proposed to serve as the heart of Markham. Businesses in the district are expected to employ up to 16,000 individuals, and it may house as many as 10,000 residents. The development plans will have a high density of residential, retail, commercial and mixed-use structures. The community is being developed, built and wholly financed by The Remington Group Inc.

Unionville is a suburban district and former village in Markham, Ontario, Canada, 2 km (2.5 mi) northeast of Downtown Markham, 2 km (2.5 mi) west of Markham Village, and 33 km (20.5 mi) northeast of Downtown Toronto. The boundaries of Unionville are not well-defined. Several nearby neighbourhoods are claimed to be part of it however, this has been disputed between the various wards.