"Recent experiments in Vienna have shown that large covalently bound complexes, composed of several hundred atoms, can be delocalized over hundred times their own size and maintain quantum coherence over many milliseconds , even when heated to several hundred Kelvin. Two major motivations are driving this research: Nanoparticle interferometry turns out to be optimized for testing new measures of quantum macroscopicity. We will discuss the molecular beam methods and coherent manipulation schemes that are required to push the current state-of-the-art by the next orders of magnitude where new bounds will be set to non-standard quantum models at the quantum-classical interface. Molecular interferograms are quantum nanorulers either in position space or in the time-domain They have an intrinsic force sensitivity down to the Yoctonewton level and are therefore well-suited for novel measurements of magnetic, structural, electronic and optical properties of molecules, clusters and other nanoparticles with widely delocalized quantum states in controlled external fields."1. K. Hornberger et al., Rev. Mod. Phys. 84, 157 (2012).2. S. Nimmrichter et al., Phys. Rev. A 83, 043621 (2011).3. S. Gerlich et al., Nature Communs. 2, 263 (2011).4. T. Juffmann et al., Phys. Rev. Lett. 103, 263601 (2009).5. S. Gerlich et al. Angew. Chem. Int. Ed. 47, 6195 (2008).6. S. Gerlich et al., Nature Phys. 3, 711 (2007).7. L. Hackermüller, NATURE 427, 711-714 (2004).