About Us German Mills Tennis Club is dedicated to providing the Thornhill community with organized tennis programs for our registered members. We offer both recreational and competitive leagues for our members as well as lessons, after-school programs and day camps. GMTC has four outdoor hard courts with full lighting for night time play, nearby parking, and a clubhouse with washrooms. The Club is located at 19 Simonston Blvd in Markham. It can be accessed behind The Church of the Good Shepherd (see map below).