An accurate Internet topology graph is important in many are as of networking,fromdecidingISPbusinessrelationshipstodi agnosing networkanomalies. MostInternetmappingeffortshavederi vedthe network structure, at the level of interconnected autonomo us systems (ASes), from a limited number of either BGP- or tracerou tebased data sources. While techniques for charting the topol ogy continue toimprove, the growth ofthe number of vantage poin ts is significantlyoutpaced bythe rapidgrowth of the Internet. In this paper, we argue that a promising approach to revealin g thehiddenareasoftheInternettopologyisthroughactivem easurementfromanobservation platformthatscaleswiththegrowi ngInternet. By leveraging measurements performed by an extensi on to a popular P2P system, we show that this approach indeed expos es significant new topological information. Based on tracerou te measurements from more than 992,000IPs in over 3,700ASes distributedacrosstheInternethierarchy, ourproposed heuri sticsidentify23,914newASlinksnotvisibleinthepublicly-availableBGP data – 12.86%morecustomer-provider links and 40.99% more peering links , than previously reported. We validate our heuristics using data from a tier-1 ISP and show that they correctly filter outallfalselinksintroducedbypublicIP-to-ASmapping. W ehave madetheidentifiedsetoflinksandtheirinferredrelations hipspublicallyavailable. Categories andSubject Descriptors C.2.3 [Computer-Communication Networks ]: Network Operations - Networkmonitoring General Terms Measurement, Management