Uncloaking of Uthero
The Uncloaking of Uthero also known as the Unmasking of Uthero was an event in Braavosi history in which the city, until then secret to the rest of the nations and realms of the world, announced its existence. It is named after Uthero Zalyne, who first dispatched envoys of the Iron Bank to Valyria to pay settlements to the grandchildren of the owners of the ships Braavos' founders had seized - but not the value of the escaped slaves - and then sent forth ships throughout the world announcing the existence and location of Braavos and inviting the men of all nations to celebrate the 111th anniversary of the city's founding.
The anniversary of the Uncloaking is still celebrated in a ten day festival of masks and revelry. In the midnight of the tenth day the Titan of Braavos roars and all celebrants and revelers remove their masks as one.