Drawing together and supplementing the structural and stichometric parallels observed beween Propertius and Virgil so far, this chapter refreshes an old debate about the genesis of Book 4 with the argument that the collection builds into itself a carefully designed Virgilian architecture. Or rather, architectures: Propertius 4 vacillates beween a ten-unit bucolic substructure and a twelve-unit epic superstructure; like the Georgics and the whole Virgilian corpus that encloses that work, it locates at its centre a Callimachean ‘Victoria Caesaris’, complete with Apolline temple; and in the ostensibly ‘Iliadic’ 4.7 and ‘Odyssean’ 4.8 it inverts the Homeric diptych of the two hexads of the Aeneid, but in a way that also recognizes the Virgilian sequence and how it is blurred. Symbolic of this protean book is Vertumnus in elegy 4.2, the shapeshifting god whose loquacious statue – the work of the Mamurius who fabricated the eleven copies of Numa’s legendary shield – not only replicates, en abyme, the book’s range of Virgilian lexis, but also encodes its Virgilian structure. A coda to the chapter shows that Ovid repeatedly draws on Vertumnus as ambassador of metamorphic elegiac-epic poetics.