The memorial is located in the arch of the bridge.

The memorial includes two inscribed plaques, a metal sculpted monument and bent pieces of railway track at the location of the bombing.

The site remembers the 300+ Allied casualties of the USAAF Bombing raid on the Orvieto North Railway Bridged (Ponte di Guilio) on January 28, 1944.  In support of the Allied landings at Anzio – Operation Shingle. Air forces attacked enemy targets that might hinder the enemy response to the landings.  The 320^thBombardment Group (Medium) was missioned to strike the Orvieto North Railway Bridge.  

From the 320th Bombardment Group (M) Daily Mission Report:

           B. At 1050 hours, 28 B-26's of the 320th Bombardment Group (M) took off (from Decimomannu, Sardinia) to bomb Orvieto RR Bridge, North, Italy. They were unescorted. 1 B-26 returned early because of engine trouble. 27 B-26's were over the target and 27 B-26's dropped 84 x 1000 lb demolition bombs (1/10,·025 second delay fuses) and 36 x 500lb demolition bombs (18-1; 18-12 hour delay fuses) on the target at 1300hrs from 11,300'. 25 B-26's returned at 1604 hrs and 2 B-26's returned at 1655 having landed at Ghisonaccia (Corsica) to refuel.

RESULTS: An excellent concentration of bombs bracketed the bridge with direct hits at the south and completely destroying 2 spans. 100ft of the bridge has been wiped out. 1 train of 40/50 cars standing across the bridge received direct hits destroying 10 cars, derailing 3 and the remainder buckled up in an arch.

From the Allerona Bridge Group Website:

The events-in-question took place on Jan. 28, 1944 when a German army train loaded with captured GIs, British Tommies and South Africans was crossing a strategically vital railway bridge over the River Paglia near the town of Allerona.

As the locomotive rumbled slowly across the narrow span, a formation of B-26 bombers from the 320th Bomb Group suddenly appeared overhead to knock out the rail line. With bombs raining down on the river gorge, the train’s crew inexplicably leapt from the engine and fled the scene on foot. The soldiers guarding the prisoners immediately followed suit, abandoning the captives in padlocked boxcars to their fate.

Over the next few minutes, more bombs fell with some striking the bridge and the railway cars themselves. Although more than 400 prisoners were killed in the ensuing inferno, others managed to free themselves and make their way to safety.

The inscription on the two plaques are written in Italian and English and read:

The left side plaque:

Fratello che passi, ricorda:
Noi siamo mori qui
Per la tua libertà

Remember this,
All you who pass by this place:
We died that you may be free.

28.01.1944 - 28.01.2012

The right side plaque:

Il 28 gennaio 1944, mentre un convoglio tedesco trasportava prigionieri britannici,
sudafricani ed americani verso i campi per prigionieri di guerra in Germania,
l'aviazione americana bombardò il ponte causando oltre 300 morti.
Questi binari, piegati dalla violenza del fuoco, restano qui a perenne memoria

On 28 January 1944, whilst a freight train was transporting British,
South African and American prisoners of war towards prison camps in Germany,
the United States Army Air Force bombed the bridge causing over 300 dead.
These rails, bent by the violence of the attack, remain here as a perpetual memory

Orvieto, Novembre 2015.