You can enter the MetLife from directly inside Grand Central Station.

If you are taking a cab, you can tell the driver to take you to Grand Central Station.  You can enter The MetLife Building from anywhere in Grand Central Station but the entrance closest to The Metlife Building entrance is on 45th Street between Lexington and Vanderbilt.
If you are taking the subway, you may take the 4/5/6/7/S Subway Lines to Grand Central Station, and then follow the signs within Grand Central pointing you to MetLife Building.
If you run into any difficulty, please don’t hesitate to give us a call at 212.729.3922.  Reception is available 7 days per week.  Thank you, and we look forward to your visit.