Phoenix Commercial R.E. has completed the $3.1 million sale of the medical office building at 21 Main St. to North Reading Realty Group. The three-story elevatored and handicapped accessible multi-tenanted property with 20,033 s/f was constructed in 1986 and completely renovated and updated for medical use in 1993. Tenants are of medical professions and represent a variety of specialty practices including several long-time doctors in the area. Mark Rosen of Phoenix represented the seller, K&R Realty Trust, and introduced the buyers, North Reading Realty Group, LLC. He is also in charge of future leasing.