100 Lessons Learned for Project Managers

"13. A project manager should visit everyone who is building anything for his project at least once, should know all the managers on his project (both government and contractor), and know the integration team members. People like to know that the project manager is interested in their work, and the best proof is for the manager to visit them and see first hand what they are doing."

http://appl.nasa.gov/ask/issues/14/practices/ask14_lessons_madden.html