1826: Road map of Paris surveyed by Charles Picquet, geographer for the King and the duke of Orléans.

-   1836: Cadastre of Paris, Philibert Vasserot. Map constructed according blocks and classified according to old districts. 24 Atlas, 1810-1836.

-   1888: Atlas of the 20 districts of Paris, surveyed by M. Alphand, and L. Fauve, under the administration of the prefect E. Poubelle, Paris, 1888.

All these maps were digitized at the LaDéHiS under the supervision of Maurizio Gribaudi, in the framework of a research on the social and architectural transformations of parisian neighborhoods between the 18th and 19th centuries. The network (and the block structure of figure 1) extracted from the Vasserot cadastre was initiated by Anne-Laure Bethe for the program Alpage [@Alpage].

The networks of 1999 and 2010 are coming from the french Geographical National Institute (IGN) on the basis of modern surveys.

**Average route distance**

For a network, the shortest path between two nodes is defined as the path with the minimum number of links connecting the two nodes. For spatial networks, it makes more sense to weight the links with their length: to each edge $e$ we thus associate a weight given by its euclidean length $d_e$. 