Cetinje is the gateway to the Lovćen National Park (Nacionalni Park Lovćen, admission €1 in summer, mausoleum €2), the 62 square kilometres of stunning mountain scenery area that forms the backdrop of the Bay of Kotor.
It's a short drive from town to the park entrance, and as you wind your way uphill you pass weird rock formations, forests and  meadows. There's good hiking here, though most visitors continue to make the steep ascent to the mountain's Jezerskom Vrhu (Lake Peak, 1,660m), 21km from Cetinj.
This barren mountaintop not only offers fantastic views of much of Montenegro and the Bay of Kotor, it also is where Petar II Petrović Njegoš’ Mausoleum (Njegošev Mauzolej) stands and where Montenegrins come to pay respect to the great statesman and poet. The 1974 building and the viewpoint are reached up a long flight of stairs tunnelled into the mountainside.