Since the plan of Paris has remained basically radial, the visitor has the choice of proceeding circumferentially along one of the lines of outer or inner boulevards or of turning inwards to the centre. It is more profitable, on the whole, to advance centripetally, for the outer boulevards are generally very monotonous. The Île de la Cité was the original core of Paris; the east-and-west axis of the Louvre, extended westward along the Champs Élysées all the way to the Étoile, already provided a central tract parallel to the Seine; the new cross axis was to be a north and south artery running from the Gare de l’Est to the Observatoire. On the Île the vast complex of the Palais de Justice, whose restoration and extension had been undertaken by Duc as early as 1840, received a notable Second Empire ornament in its western block, facing the Place d’Harcourt, which was built by Duc assisted by E.-T. Dommey (1801-72) in 1857-68. Rationalistic in its structural expression and Classical in most of its detailing, this façade and the hall behind it reflect the tastes of the period in the heavy scale of the parts and the rather cranky—and certainly studied—awkwardness of the modelling of the various conventional elements of the orders and minor features of detail. Duc’s earlier work at the Palais de Justice, on the other hand, was detailed with very great grace and elegance, it may be noted. The principal Second Empire construction on the east-and-west axis of Paris, the New Louvre, has been described already. Along the north side of the Louvre the Rue de Rivoli was extended eastward in 1851-5 the entire length of the palace with no change in the original Percier and Fontaine design except for the addition of high quadrantal mansards throughout the entire length of the street and its subsidiaries. Even a large new hotel[186] was forced into this framework. Yet because of its island site, the high rounded roofs give this block as it is usually seen from the Place du Théâtre Français to the north something of the new plasticity; it thus provided eventually an appropriate terminus to the Avenue de l’Opéra, after that was finally completed under the Third Republic. Facing the east side of the Louvre, Hittorff balanced the restored Gothic front of Saint-Germain-l’Auxerrois with the new front of the Mairie du Louvre built in 1857-1861. Characteristic of this period in France is the avoidance of Gothic detail on this secular façade in favour of something vaguely _François I_; yet the pattern of the front of the church is carefully repeated, even to the rose-window in the high-pitched gable, and the new tower by Ballu, on axis between the Church and the Mairie, is Gothic.