How Imaging Quasars Improved GPS Accuracy

What do distant quasars have to do with improving GPS accuracy? A 2019 article from the NASA Technology Transfer Program explains: “In the 1960s, NASA used a network of radio telescopes and a technique called very large baseline interferometry (VLBI) to capture images of quasars in distant galaxies. In the following decade, scientists reversed the process to determine the precise locations of the telescopes, painting a picture of Earth’s shape and orientation in space. Today, an evolution of that technology supports another location-based system that has arguably become the world’s most important communication infrastructure: the Global Positioning System (GPS).” [Ariel Waldman]

300,000 Kilometres of Roman Roads

Itiner-e is a comprehensive digital atlas and dataset of the Roman Empire’s entire road network, based on fieldwork, existing maps, published data and remote sensing. It’s an attempt to provide more granular detail than past atlases of Roman roads such as the Barrington Atlas (the iPad edition of which I reviewed in 2013), and expands the known Roman road network to nearly 300,000 km. The flip side is that less than three percent of it is known precisely. The dataset rates the certainty of each road segment, and a lot of them are marked as conjectured or hypothesized (i.e., there is evidence that there was a road here somewhere). It’s meant to be refined over time with additional research. More at the article published in Scientific Data; news coverage at La Cartoteca, Euronews and Gizmodo.

Mapping the 2025 (and 2021) Canadian Election Results

Jacob Weinbren has mapped the results of the 2025 Canadian federal election at the polling station level, along with the 2021 results so that we can see how the vote changed. Any project of this kind is going to be insufficient along some axis: because it shows percentages rather than raw votes and is a geographical map, it doesn’t represent the number of votes cast very well, and tracking six parties is a lot for a choropleth map. But for the purposes of seeing the change in voting patterns from 2021 to 2025, it works: I can tell at a glance, for example, that reserves on the Prairies got more Liberal, and my own neck of the woods got a lot more Conservative. Direct link to map here.

More on Secret Maps

Doug Specht has a piece about the British Library’s exhibition Secret Maps in The Conversation. “The exhibition does not shy away from difficult topics. Maps tracing the infrastructure of apartheid, or those produced to facilitate war or surveillance, sit alongside playful artefacts such as the iconic Where’s Wally? books. The effect is to remind us that all mapping, whether for adventure, statecraft, or protest, is fundamentally about control: who gets to see, who gets seen and who decides.”

I’d forgotten that past British Library exhibitions (London: A Life in Maps, Magnificent Maps) generated all kinds of coverage. This might not be the last piece we see on this exhibition.

Previously: New British Library Exhibition: Secret Maps; Secret Maps, the Book.

Ireland: Mapping the Island

RTÉ has published an excerpt from Ireland: Mapping the Island by Joseph Brady and Paul Ferguson, the latest book of cartographic histories published by Birlinn (though Birlinn’s website seems to be offline at the moment).

Book cover: Ireland: Mapping the Island

This book – Ireland – Mapping the Island – is a celebration of the maps of Ireland produced over the centuries. We aim to give our readers a sense of the huge variety of maps that have been drawn and of their value as documents. Quite a number of themes run through the book. We look at the importance of boundaries, what maps tell us about the development of towns and settlements, the ways in which maps have been used to create impressions of place, their role in the development of travel and how they facilitated the emergence of the ‘tourist’. We also look at how others saw us and particularly at the maps produced since the 1930s by the military powers of a number of countries. One central focus is on how we learned about the shape and internal geography of Ireland. Before the development of airplanes and spacecraft, people had to take it on trust that we correctly knew the shape of the island of Ireland. That knowledge had been gradually refined for centuries and the state of knowledge was captured in the maps produced in each era.

Ireland: Mapping the Island by Joseph Brady and Paul Ferguson. Birlinn, 2 Oct 2025 (U.S. 2 Dec 2025), £30/$45. Amazon (CanadaUK), Bookshop.

Secret Maps, the Book

Both the U.K. and U.S. covers of Secret Maps, a book accompanying a British Library exhibition of the same name.

I didn’t put two and two together. Secret Maps, the British Library exhibition (previously), has an accompanying book, because British Library exhibitions invariably come with books. And that book was already listed on my Map Books of 2025 page: Secret Maps: How they Conceal and Reveal the World by Tom Harper, Nick Dykes, and Magdalena Peszko, who curated the exhibition, is out now from British Library Publishing; it comes out in the U.S. in a couple of weeks, under the title Secret Maps: Maps You Were Never Meant to See, from the Middle Ages to Today, from the University of Chicago Press.

Secret Maps by Tom Harper, Nick Dykes and Magdalena Peszko. British Library, 24 Oct 2025, £40. University of Chicago Press, 14 Nov 2025, $39. Amazon (Canada, UK), Bookshop.

A Street Map of Early Modern Europe

Viabundus is an online map of medieval Europe.

Viabundus is a freely accessible online street map of late medieval and early modern northern Europe (1350-1650). Originally conceived as the digitisation of Friedrich Bruns and Hugo Weczerka’s Hansische Handelsstraßen (1962) atlas of land roads in the Hanseatic area, the Viabundus map moves beyond that. It includes among others: a database with information about settlements, towns, tolls, staple markets and other information relevant for the pre-modern traveller; a route calculator; a calendar of fairs; and additional land routes as well as water ways.

Viabundus is a work in progress. Currently, it contains a rough digitisation of the land routes from Hansische Handelsstraßen, as well as a thoroughly researched road network for the current-day Netherlands, Denmark, the German states of Lower Saxony, Schleswig-Holstein, Thuringia, Saxony-Anhalt, Brandenburg, Mecklenburg-Vorpommern, Hesse and North Rhine-Westfalia, and parts of Poland (Pomerania, Royal Prussia, Greater Poland). The pre-modern road network of Denmark will be added soon; the inclusion of other regions is currently being planned.

What features would an online map service have, if online map services existed in early modern Europe? Something like this. I tried the route calculator: I found that it would take me approximately 20 days to get from Frankfurt to Antwerp on horseback in 1500. (It’s about four and a half hours by car today, per Google Maps.) People who write historical fiction set Europe in this time period ought to be all over this. [MetaFilter]

New British Library Exhibition: Secret Maps

Banner illustration from the British Library’s Secret Maps page.
British Library

A new exhibition opened at the British Library this weekend: Secret Maps.

Maps have always been more than just tools for navigation – in the hand of governments, groups and individuals, maps create and control knowledge. In Secret Maps, we trace the levels of power, coercion and secrecy that lie behind maps from the 14th century to the present day, and uncover the invisible forces that draw and distort the world around us.

Some of the maps on display reveal hidden landscapes, offering insight into places long forgotten or erased from official histories. Others are purposefully deceptive, designed to protect treasures, mask strategic locations, or reshape the way we see the world. This exhibition uncovers each of their individual secrets, revealing their hidden purposes and power.

The exhibition runs until 18 January 2016. Tickets cost £20. There are also a number of talks, tours, workshops and other events affiliated with the exhibition; they’re listed at the bottom of the exhibition’s web page.

Update: There’s also a book.

Update #2: Strike action by British Library workers may affect opening hours. See this page for information.

Ads Coming to Apple Maps: Report

An update on ads coming to Apple Maps. AppleInsider, citing a paywalled report from Mark Gurman’s Power On newsletter: “[T]he decision has been taken to move ahead with the project. The claim is that starting as soon as 2026, Apple will allow businesses to pay to have their entries in some way displayed more visibly within Apple Maps.”

Previously: Apple Exploring Advertising in Maps.

More on the Exhibition of Le Guin’s Maps

Mike Duggan takes a look at the exhibition of Ursula K. Le Guin’s maps currently running at the Architectural Association Gallery in London, which displays the maps as cyanotypes on fabric.

Book cover: The Word for World

In the gallery space, Le Guin’s maps are looked at in isolation rather than relating directly to a text. They demand a different kind of attention, for there is a different form of visual connection between a viewer and a gallery object than between a reader and a book. So the maps are taken out of their original context and placed in another. But this isn’t to say this new context is any less significant. […]

There will forever be a tension between the map exhibition and the ways that maps are encountered in books. By definition they are being “exhibited” and put at the centre. And there’s no doubt Le Guin’s maps look impressive here, masterfully hung, printed on deep blue cotton, bathed in warm lighting.

Draped thoughtfully in rows throughout the space is perhaps a nod to being immersed in the cartographic imagination of Le Guin. They are certainly a spectacle that encourages a closer look. But is that enough?

The exhibition runs through 6 December. The accompanying book is out now from Spiral House (and in the U.S. in January): Amazon (CanadaUK), Bookshop.

Previously: The Word for World: The Maps of Ursula K. Le Guin.