Understanding the Internet's topological structure continues to be fraught with challenges. In this paper, we investigate the hypothesis that physical maps of service provider infrastructure can be used to effectively guide topology discovery based on network layer TTL-limited measurement. The goal of our work is to focus layer 3-based probing on broadly identifying Internet infrastructure that has a fixed geographic location such as POPs, IXPs and other kinds of hosting facilities. We begin by comparing more than 1.5 years of TTL-limited probe data from the Ark project with maps of service provider infrastructure from the Internet Atlas project. We find that there are substantially more nodes and links identified in the service provider map data versus the probe data. Next, we describe a new method for probe-based measurement of physical infrastructure called POPsicle that is based on careful selection of probe source-destination pairs. We demonstrate the capability of our method through an extensive measurement study using existing "looking glass" vantage points distributed throughout the Internet and show that it reveals 2.4 times more physical node locations versus standard probing methods. To demonstrate the deployability of POPsicle we also conduct tests at an IXP. Our results again show that POPsicle can identify more physical node locations compared with standard layer 3 probes, and through this deployment approach it can be used to measure thousands of networks world wide.