Gates: York Watergate
This gateway marks the position of the north bank of the River Thames before the construction of the Victoria Embankment in 1862. It was built in 1626 by Nicholas Stone, master mason, for George Villiers, 1st Duke of Buckingham, to serve as the watergate to York House which the Duke had acquired from the Archbishop of York in 1624. The arms on the river front and the motto "Fidei cotucula crux" (the cross is the touchstone of faith) on the land side, are those of the Villiers family. York House was demolished in 1675 and streets were laid out on the site. In 1893 the gate having fallen into decay, the London County Council obtained parliamentary powers to acquire and preserve it as an object of public interest.
The streets laid out on the site of York House were named: Villiers Street, Duke Street, Buckingham Street, George Court and Of Alley (now York Street). That's known as making use of everything.
Site: York Watergate (1 memorial)
WC2, Victoria Embankment Gardens
Now 100 metres away from the Thames, this used to be where boats would pull in to allow passengers to disembark for York House. Those waiting for the boat could shelter in the two side arches. Baldwin Hamey has a good post on this gate and the local area.