But the centres operated at significant loss last year.
The Office of Public Works spent almost one and a half million euro staffing and maintaining three monuments in the midlands last year.
However, details released under the Freedom of Information Act show the sites operated at a significant loss in 2019.
Clonmacnoise had costs of over €610,000, compared to about €530,000 in visitor income.
Spending at Portumna Castle was just shy of €600,000, with an intake of €42,000.
While Roscrea Heritage Centre spent almost €200,000 and took in less than €4,000.