Mayo native Charlie Kenny (83) and his wife and five children owe their wealth to a portfolio of properties in Dublin city centre which were valued at more than €470m in 2016.
They are held in a series of unlimited companies, which shields their accounts from public scrutiny. They will have since increased in value. One of the firms, Clancourt Holdings, aims to build a nine-storey office building at the junction of Charlemont Street and Harcourt Road in the capital, which could house up to 3,000 workers.
They also intend to convert three former nightclubs nearby - Crawdaddy, Tripod and the Chocolate Bar into a mixed-use restaurant, retail and office development.
Sons Conor and Kevin manage the group, whose tenants include Dropbox, Aviva and Arthur Cox. The family also own a Limerick shopping centre.