Businesses
- A and J Main Limited
- A and J Robinson
- A and R Thwaites and Company Limited
- A and S Henry and Company Limited
- A Armstrong and Company Limited
- A Baily and Company Limited
- A Baverystock and Company
- A Miller and Company Limited
- A Miller and Son
- Abbey Bar
- Abbey Theatre
- Adelaide Hospital
- Adelaide Sullivan, confectioner
- Adelphi Hotel
- Aerators Limited
- AG Bagot and Company
- AG Campbell and Sons
- Agnes K Morgan, grocer
- Aillebrack National School
- AJ Caley and Son Limited
- Albert E Bennett and Company Limited
- Alex Findlater and Company Limited, provision merchants
- Alex Pirie and Sons Limited
- Alexander and Company, tailor
- Alexander Marks and Sons Limited
- Alexander Ramsay Limited
- Alexander Thom and Company Limited
- Alexandra Club
- Alfred Jay and Son
- Alien Internment Camp
- All Hallows College
- Allen and Hanburys Limited
- Alliance and Dublin Consumers Gas Company
- Alliance Assurance Company Limited
- Almond's Hotel
- Amalgamated Union of Cabinet Makers
- American Lead Pencil Company
- Amiens Street Railway Station [Connolly Station]
- Ancient Guild of Incorporated Brick and Stonelayers Trade Union
- Ancient Order of Hibernians
- Anderson, Stanford and Ridgeway Limited
- Andrews and Company Limited
- Angus Watson and Company
- Anne Lynch and Company
- Anthony O'Neill and Son, undertakers
- Apperly Curtis and Company Limited
- Architects' Golfing Association
- Ardath Tobacco Company
- Aries and Company
- Armstrong and Company Limited
- Army and Navy Veterans Association
- Army Pay Corps
- Arnott and Company Limited
- Arthur Guinness Son and Company Limited
- Ashanti Goldfield Corporation Limited
- Association for Discountenancing Vice and Promoting the Knowledge and Practice of the Christian Religion
- Association of Irish Post Office Clerks
- Association of Irish Unestablished Clerical Civil Servants
- Attorneys and Solicitors of Ireland
- AY Haynes