Castel Tealdo or Thealto was a former medieval castle forming part of the defenses of Ferrara. Few traces of its existence remain. The castle stood along the river, west of the town, as did the Castel Novo, and was built in the 10th century by Tealdo da Canossa, Count of Modena and son of

Otto I, Holy Roman Emperor Otto I (23 November 912 – 7 May 973), traditionally known as Otto the Great (german: Otto der Große, it, Ottone il Grande), was East Francia, East Frankish king from 936 and Holy Roman Emperor from 962 until his death in 973. He was the olde ...

. In 1317, the city rebelled against the rule of

Robert, King of Naples Robert of Anjou ( it, Roberto d'Angiò), known as Robert the Wise ( it, Roberto il Saggio; 1276 – 20 January 1343), was King of Naples, titular King of Jerusalem and Count of Provence and Forcalquier from 1309 to 1343, the central figure of Ita ...

, and locals overpowered the Catalan mercenaries who had taken shelter in the castle. This led to the admission of the Este to Ferrara. The castle was then rebuilt by

Alberto d'Este Alberto (V) d'Este (27 February 1347 – 30 July 1393) was lord of Ferrara and Modena from 1388 until his death. He was associated in the lordship of the House of Este by his brother Niccolò in 1361, becoming the sole ruler of Ferrara and ...

in 1395. In 1597-1608, this castle and the churches of San Giovanni Battista and Sant'Agata were razed to build a papal fortress. The Castel Nuovo was razed in 1562.Herculean Ferrara: Ercole D'Este (1471-1505) and the Invention of a Ducal Capital
by Thomas Tuohy, page 46. The papal fortress was razed in the 19th century.

References

{{coord missing, Italy Buildings and structures in Ferrara Demolished buildings and structures in Italy