Map construction and task-oriented navigation constitute two important capabilities for mobile robots. Despite their value, progress to date in the development of stand-alone robots endowed with these capabilities has been limited. We describe an architecture for mobile robots based on the concept of semi-autonomy that employs communication with a human advisor in order to simplify the tasks of map construction and navigation. Communication can be used both by the human to convey information to the robot that is beyond its own perceptual capabilities and by the robot to extract information from the advisor that may be required in the execution of an assigned task. The semiautonomous philosophy has two main benefits, namely a de-emphasis on the notoriously difficult subtask of perception and an overall increase in flexibility.