  Real estate projects are developed excessively in China in this decade. Many
new housing districts are built, but they far exceed the actual demand in some
cities. These cities with a high housing vacancy rate are called ghost cities.
The real situation of vacant housing areas in China has not been studied in
previous research. This study, using Baidu positioning data, presents the
spatial distribution of the vacant housing areas in China and classifies cities
with a large vacant housing area as cities or tourism sites. To the best of our
knowledge, it is the first time that we detected and analyzed the ghost cities
in China at such fine scale. To understand the human dynamic in ghost cities,
we select one city and one tourism sites as cases to analyze the features of
human dynamics. This study illustrates the capability of big data in sensing
our cities objectively and comprehensively.
