If you like to learn more about Past, just purchase a ticket and move across the River. But if you like to find ONLY the Cache, just proceed to Toilettes. When 'nature calls' nobody stops you. But ... move ahead, past toilettes (first floor) and see the view from above. Obviously, you are not interested into views ... But you may take some pictures from above. And search for the cache - a little one, magnetic, hidden near the second pillar.