He is known today chiefly for his Forma Urbis Romae (1893‑1901) and the Storia degli scavi, a regular summary of Roman excavations that started appearing in 1902.
He was a member of the Accademia dei Lincei, the Academia di S. Lucia, the Berlin Institute, the Royal Academy of Belgium, and the Archaeological Society of Brussels.
[7] Lanciani formed a core of distinguished late nineteenth-century scholars of the Roman Forum including Henri Jordan, Christian Huelsen, Samuel Ball Platner, and Thomas Ashby.
The modern Atlas of Ancient Rome by Andrea Carandini is a "systematic update... and a reformulation of the information" of Lanciani's Forma Urbis.
3,000 volumes of documentation were bequeathed to the National Institute of Archaeology and Art History in Rome upon Lanciani's death in 1929; the collection occupies its own room in the Palazzo Venezia.