We will be in Paris in June with 16 year old twins - a boy and a girl. My son wants to do as much climbing as he can e.g. Eiffel by stairs. Is it safe to let him do the stair route while we take the lift. We won't be in telephone contact. I am worried about getting lost. What other sights have lots of stirs to climb. Is there any place where I can leave the teenagers for an hour or two while my husband and I go somewhere else?