NEW YORK and DUBLIN — It wowed crowds, joined up families and created more than a little controversy, but a new visual art installation linking New York and Dublin has certainly been a talker. 

Called “The Portal,” a giant screen and video camera have been placed next to the Big Apple’s famed Flatiron Building and another in O’Connell Street, the Irish capital’s main thoroughfare.

Each sculpture broadcasts a livestream from the portal in the other city, allowing real time…