The Nolli Map of Rome is one of history’s most famous works of cartography, and now a new iPhone and iPad app lets you use it to navigate in realtime, helping you both lose and find yourself in one of Europe’s most marvelous ancient cities.

Finished in 1748 after 12 years of research by Italian architect and surveyor Giambattista Nolli, this innovative map represented a novel approach to figure-ground representation. Streets and open public spaces were, for instance, predictably depicted as voids against a backdrop of solid hashes, but so to were enclosed civic spaces like the Pantheon.

The original engraved city map consisted of 12 copper plates spanning 40 square feet, and, at the time, was the most accurate representation of the city to date. Honoring that tradition, this digital experience replicates many original features and details from the vintage original.

So why would you want to tour modern Rome with a centuries-old map? Its creator, Martin Koppenhöfer, explains that “despite its age, this map is still very valid for most parts of the Roman center.” He also notes that “it is quite entertaining to find your way with this app. Pedestrian navigation is very different … you don’t have to know every street or turn, just go into the right direction.”

Think of it as part walking tour, part adventure and part historical education. Using an old map to navigate a city lets you find things that might have otherwise escaped your attention. It also allows you to distinguish between more permanent fixtures of the historic built environment and more contemporary changes and additions. If you lack a compatible device for the app, you can also check out an online interactive (but less mobile) version of this iconic map.

“In designing the present edition,” Koppenhöfer elaborated in and interview with WebUrbanist, “we have spent great care with the aim to be as close to the original as possible regarding the labeling and the structure of the directories. Therefore the app reproduces in the indices on the left side of the map exactly those types in the exact order and (to the contemporary reader occasionally appearing outmoded) notation as provided by Giambattista Nolli in his indices. By selecting an entry you will be led to the corresponding location on the map. You can also browse by tapping on one of the numbers on the map to see what it is about.”

The original version is meticulously adhered to, providing an updated digital experience while maintaining original notes and styles. “The explanations of the signatures and line styles,” says Koppenhöfer, and “hatches and selected abbreviations are reproduced in their original form (see “Legend”). You can access Nolli’s original spelling of the indices, legend, and other signs at the bottom of the English version in Italian language.”