What Irish city's name is Gaelic for "black pool"?

Dublin  is the capital and largest city of Ireland. Dublin is in the province of Leinster on Ireland's east coast, at the mouth of the River Liffey. The city has an urban area population of 1,345,402. The population of the Greater Dublin Area, as of 2016, was 1,904,806 people.

The name Dublin comes from the Irish word Dubhlinn, early Classical Irish Dubhlind meaning "black, dark", and lind  "pool", referring to a dark tidal pool. This tidal pool was located where the River Poddle entered the Liffey, on the site of the castle gardens at the rear of Dublin Castle. In Modern Irish the name is Duibhlinn, and Irish rhymes from Dublin County show that in Dublin Leinster Irish it was pronounced Duílinn. The original pronunciation is preserved in the names for the city in other languages such as Old English Difelin, Old Norse Dyflin, modern Icelandic Dyflinn and modern Manx Divlyn as well as Welsh Dulyn.

Dublin celebrated its 'official' millennium in 1988 AD, meaning that the Irish government recognized 988 AD as the year in which the city was settled and that this first settlement would later become the city of Dublin.