I walked a lot (36 km!) during the first day. Walked from the hostel (outside of the centre), to Notre-Dame, from there to a restaurant, from there to Arc de Triomphe, from there to the Eiffel Tower, from there to Louvre, from there back to Notre-Dame, and from there back to the hostel. The next day, I walked to Parc de Belleville, then took the metro from there to the Eiffel Tower, walked from the tower to Luxembourg Gardens, from there to a restaurant (where I met up with Dave), and then back to the hostel. (I walked 17 km this day.) The last day, I spent the whole day relaxing at the hostel, and didn't go out until the evening. Walked to a restaurant and then back to the hostel.