Characterizing the flow of Internet traffic is important in a wide range
of contexts, from network engineering and application design to
understanding the network impact of consumer demand and business
relationships. Despite the growing interest, the nearly impossible task of
collecting large-scale, Internet-wide traffic data has severely constrained
the focus of traffic-related studies.
In this paper, we introduce a novel approach to characterize inter-domain traffic by reusing large, publicly available traceroute datasets. Our approach builds on a simple insight -- the popularity of a route on the Internet can serve as an informative proxy for the volume of traffic it carries. It applies structural analysis to a dual-representation of the AS-level connectivity graph derived from available traceroute datasets. Drawing analogies with city grids and traffic, it adapts data transformations and metrics of route popularity from urban planning to serve as proxies for traffic volume. We call this approach Network Syntax, highlighting the connection to urban planning Space Syntax. We apply Network Syntax in the context of a global ISP and a large Internet eXchange Point and use ground-truth data to demonstrate the strong correlation ($r^2$ values of up to 0.9) between inter-domain traffic volume and the different proxy metrics. Working with these two network entities, we show the potential of Network Syntax for identifying critical links and inferring missing traffic matrix measurements.