Wikidata Atlas is an online system that allows users to explore Wikidata items
on an interactive global map; for example, users can explore the global
distribution of all lighthouses described by Wikidata. Designing such a system
poses challenges in terms of scalability, where some classes have hundreds of
thousands of instances; efficiency, where visualisations are generated live;
freshness, where we want changes on Wikidata to be reflected as they happen in
the system; and usability, where we aim for the system to be accessible for a
broad audience. Herein we describe the design and implementation of the system
in light of these challenges.