A lot of Modernist houses you love from the 1950's and 1960's are going the way of unfortunate "renovations" or the bulldozer, largely because few people are aware of their architectural significance.  Although most houses by famous architects are on lists, it's difficult to find where they are actually located. We talk with two expert house trackers who have between them documented thousands of houses and flown tens of thousands of miles to visit them! Jan-Richard Kikkert is an Amsterdam-based architect and head of the Architectural Department of the Amsterdam Academy of Architecture. He has visited every project designed by John Lautner, over 300 from Los Angeles to Aspen and from Anchorage to Acapulco.  He is Head of Architecture Department at the Amsterdam University of the Arts and a member of the Board of Advisors of the John Lautner Foundation.  He was in the documentary Infinite Space: The Architecture of John Lautner. Paul Moore is a former architect turned IT professional. He graduated with a BS in Architecture from the University of Michigan in 1986 and moved to Los Angeles to study at SCI-ARC. He started working on the digital version of Sweet's Catalogs for several years and in 2007, began using online mapping tools to locate public art and architecture posting to VirtualGlobeTrotting.com.  He has searched for and found nearly 11,000 houses!