Titus Lucretius Carus - De Rerum Natura (On the Nature of Things)
Biblioteca Malatestiana in Cesena. Unfortunately I don't know how old this copy is.

Neume initial
Biblioteca Malatestiana, Cesena.

Etymologiae by Isidore of Seville
Originally from the 7th century. This is a copy from the 8th century in Carolingian minuscule script. In Biblioteca Malatestiana in Cesena.