An apparatus and method for access to the inside of a body includes a transparent sheath with a radiopaque marking and fastener for securing a guidewire or catheter. The transparent sheath permits objects located within and near the sheath to be visualized with an external imaging system. Objects located near the sheath can also be observed with an imaging device disposed inside the sheath. The radiopaque marker permits accurate positioning of the sheath in the body. The sheath can be inserted into the body over an interventional device. A fastener prevents migration of a guidewire or catheter during the procedure.