The main entrance to Muir Woods, which features the Muir Woods Visitor Center, is on Muir Woods Road — a winding road down to the valley floor from Panoramic Highway above. While you do need a Muir Woods parking reservation if you want to park your car in the lot at the entrance, you don't need a reservation to actually enter Muir Woods. You can simply buy a Muir Woods entrance ticket at the gate or in advance online with your parking reservation.