Plans by trade union Siptu to demolish and redevelop Liberty Hall in Dublin have been rejected by the planning appeals authority.
An Bord Pleanála said the the new complex would be “unacceptably dominant” in the city and “visually intrusive in the streetscape and riverscape”.
The authority was also of the view the proposal would “seriously injure the visual amenities of the city and its skyline”.
“Furthermore, the proposed development would seriously detract from the setting and character of the Custom House, would intrude on the O’Connell Street and Grafton Street Architectural Conservation Areas, and other important vistas in the city.
“The proposed development would, therefore, be contrary to the proper planning and sustainable development of the area.”
Siptu had planned to build a new 22-storey structure about 100m high. It would have included office space, a conference auditorium and a rooftop heritage area. The structure would have been more than half as tall again as the existing building, and 1.5 times wider.
The board said it had unanimously decided to refuse permission in accordance with planning inspector Mary Crowley’s recommendation.
Siptu said it was "extremely disappointed" with the decision.
“The union, our architects and professional advisers have put five years' hard work into this project including an enormous amount of consultation with Dublin City Council, our members and other key stakeholders including the local community and their public representatives," general secretary Joe O'Flynn said in a statement.
"Given that the city council saw fit earlier this year to grant us planning permission for the redevelopment of Liberty Hall, we are extremely disappointed that this decision has now been overturned by An Bord Pleanála."
Dublin City Council gave approval for the project last February but a number of appeals were subsequently lodged to An Bord Pleanála.
An Taisce called for an independent regulator to be appointed to investigate the planning function of Dublin City Council.
Charles Stanley-Smith, communications officer and former chair of the trust, said the refusal of the Liberty Hall application was on the same grounds as that of the Mater site proposal for the National Children's Hospital earlier this year.
"This decision again raises the wider question as to why Dublin City Council is found to have once again breached its own development plan and national policy and the lack of an independent investigation thereof," said Mr Stanley-Smith.
"An Taisce is now seeking an independent planning regulator to undertake this investigation and to extend it into the city council's endorsement of the failed National Children's Hospital and Liberty Hall plans.
"It is a waste of time and scarce resources for major applications to be processed through the planning system, if they are then overturned because they are found to be in breach of local and national policy."