Markham Square Condos Markham is a new condo project by Ideal Developments, ONEPIECE Developments and is currently in preconstruction. The new development will be located at 28 Main Street Unionville, Markham ON L3R 0W7. It is in Unionville city of Markham. The Estimated occupancy of Markham Square Condos is in April 2021. Sales of Markham Square Condos From $321,900 CAD.