Understanding the morphology of an urban system is an important step toward
unveiling the dynamical processes of its growth and development. At the
foundation of every urban system, transportation system is undeniably a crucial
component in powering the life of the entire urban system. In this work, we
study the spatial pattern of $73$ cities across the globe by analysing the
distribution of public transport points within the cities. The analysis reveals
that different spatial distributions of points could be classified into four
groups with distinct features, indicating whether the points are clustered,
dispersed or regularly distributed. From visual inspection, we observe that the
cities with regularly distributed patterns do not have apparent centre in
contrast to the other two types in which star-node structure, i.e. monocentric,
can be clearly observed. Furthermore, the results provide evidence for the
existence of two different types of urban system: well-planned and organically
grown. We also study the spatial distribution of another important urban
entity, the amenities, and find that it possesses universal properties
regardless of the city's spatial pattern type. This result has one important
implication that at small scale of locality, the urban dynamics cannot be
controlled even though the regulation can be done at large scale of the entire
urban system. The relation between the distribution of amenities within the
city and its spatial pattern is also discussed.