Columbus & Over Group

Advisor Profiles

Mark Callahan

Real Estate Advisor

Mark has been working in Boston’s real estate development and construction industries since 2010. Currently, Mark is an Associate with CIM Group, focusing on large scale commercial and multi-family developments in the Boston area. Previously, Mark worked as a Project Manager for New Boston Ventures, one of the premier boutique real estate developers in Boston. Mark got his start in Boston with Suffolk Construction, and is also a licensed contractor in the state of Massachusetts.

Drawing upon his experience as both a developer and a contractor, Mark brings a unique perspective to all of his clients. His pragmatic approach and diligence make him an ideal adviser for any client.

Mark earned his undergraduate degree in business economics from Brown University and has a Masters Degree in Real Estate Development from MIT. Mark and his wife Katie reside in the South End.

Jeff Hamilton

Founder and Managing Principal


Joe Castro

Real Estate Advisor


Jamie Gaines

Real Estate Advisor


Lisa Ha

Real Estate Advisor


Jonathan Russell

Real Estate Advisor


Kerry D’Ambroise

Real Estate Advisor

978 821 2187

Hailey Lowenstein

Video Producer & Multimedia Designer

Is COG Right For You?

Interested in joining the COG team? At Columbus & Over, we value our agents just as much as we value our customers. Tell us why you would make a good addition to our team.