In 1790, Ledwich published his
Antiquities of Ireland. It was later discounted, because of the imperfect information on Irish history current in his day, and his theories were effectually set aside by
George Petrie and later writers. In the index to
John Lanigan's
Ecclesiastical History there are errata to Ledwich. His article on the
History and Antiquities of Irishtown and Kilkenny, published in 1781, was appended to the second edition of his
Antiquities of Ireland, 1804. In 1791, Ledwich completed the editing and publication of his friend
Francis Grose's
Antiquities of Ireland. ;Publications • • , with Francis Grose • • ==Family==