Abstract: Methods and devices for visualizing and accessing a region inside a body are described. One embodiment of a device includes a working catheter which slides along an open track in a visualization catheter. The visualization catheter is inserted into the body to locate a region of the body with the aid of the visualization element. The working catheter then slides along the track to reach the region, and a working element is inserted through the working catheter to access the region, again with the aid of the visualization element. The methods and devices may also be used to access a variety of internal cavities, soft tissues and organs, and the mediastinal space.