IP geolocation is essential for various location-aware Internet applications. High-quality IP geolocation landmarks play a decisive role in IP geolocation accuracy. However, the previous research works focusing on mining landmarks from the Internet are hampered by limited quantity, poor coverage, and insufficient landmark quality. In this paper, we present a new framework called ProbeGeo to mine high-quality landmarks automatically. We divide landmarks into common landmarks and probe landmarks, providing systematic mining methods based on online retrieval and web content. ProbeGeo expands traditional common landmarks by taking advantage of the exposure of multiple IoT (Internet of Things) devices on the Internet, mining them based on search engines and webpage contents. Common landmarks, consisting of multi-type devices, significantly improve landmark quantity and coverage. Furthermore, ProbeGeo establishes a methodology for acquiring new probe landmarks from Internet VPs (Vantage Points) webpages, extracting geographical locations from heterogeneous webpages and utilizing active probe functions. Probe landmarks enhance landmark quality and functions, bringing new geolocation frameworks and breaking through the geolocation accuracy bottleneck. We develop the ProbeGeo as a continuously running system and conduct real-world experiments to validate its efficacy. Our results show that ProbeGeo can detect 89,849 high-quality landmarks, including 6,874 probe landmarks and 82,975 common landmarks. ProbeGeo landmarks are about 10x more than existing work, distributed in 181 countries and 7,094 cities. ProbeGeo landmarks cover more than 8 types of devices, and more than 60% of them remain stable over one month. Moreover, the landmark accuracy of more than 58% of ProbeGeo landmarks is above street level, which has not been achieved in previous works. ProbeGeo can provide geolocation services with higher landmark accuracy and broader coverage by correlating a large scale of la...