 Complete the following phrase:  It was The 3rd Marquess of Donegall who finally sold off almost all of his familys Belfast estate in the 1850s. This left, of the Belfast estate, only the Ormeau Demesne and most of Cave Hill in the ownership of Lord Donegall. Curiously, it was only when he no longer owned Belfast that Lord Donegall became interested in actually living there. He decided to build what has been described as a new princely mansion for himself in the 1860s on what was then the northern edge of Belfast, just over a decade after the 