A 42-unit apartment complex that is billing itself as "the first major development along the MBTA Green Line extension" is set to break ground on Monday morning in Medford. Mayor Stephanie Burke is the guest of honor.

The complex, which developer Peter L. Miller has dubbed the Sphere, will have 22 1- BRs and 20 2-BRs. The apartments will range from 620 square feet to more than 1,000 square feet, and will include touches such as central air and balconies.

The Sphere will also be a short distance from the future Ball Square Green Line stop, one of six new stations slated for along the 4.7-mile extension through Somerville into Medford (the existing Lechmere stop will also be relocated as part of the extension).

Cost overruns and management mishegoss have famously dogged the Green Line project, though it still appears to be a go. Projects such as the Sphere certainly hope so. It’s scheduled to open in 2017, about three years before the trolley extension is supposed to be finished.

Sphere renderings and rents to come. Stay tuned.