Westbound: From Rt. 28 passes Bel Pre Rd. and Bauer Dr, make a left on Baltimore Rd. Stay on Baltimore for ~1.0 mile, make a right turn on Avery Rd. (This is not the Avery Rd. off Rt. 28!!) Drive through some hills on Avery for ~0.3 mile, the tennis courts are to your left.
Eastbound: From Rt. 28, passes the intersection of Veirs Mill Rd. and make a right onto Baltimore Rd., you will see the sign of Rockville Civic Center at the stop sign. Enter the Civic Center at your left front and follow the main road until you see the tennis courts to your right.