The Rocca Albornoz is a square 14th-century fortress built by Cardinal Gil de Albornoz in 1354 to reassert papal authority in the city after the papacy returned to Rome. It stands at the northern edge of the historic centre near the Porta Fiorentina and now houses the Museo Nazionale Etrusco — the national Etruscan museum of Viterbo.
The museum's collection covers the Etruscan civilisation that preceded Rome across this entire part of central Italy. Viterbo sat at the heart of Etruscan territory: finds from nearby necropolises fill the galleries with terracotta sarcophagi, bucchero pottery, bronze jewellery, and stone sculpture. The display puts the local landscape into deep historical perspective — the roads, the volcanic lakes, and the hilltop towns were all Etruscan before they were Roman.
The fortress itself is worth seeing for its architecture; the courtyard retains its medieval form, and views from the ramparts take in the roofscape of the old town.