Princes Street Gardens is a public park in the centre of Edinburgh, Scotland, in the shadow of Edinburgh Castle. The Gardens were created in two phases in the 1770s and 1820s following the long draining of the Nor Loch and building of the New Town, beginning in the 1760s. The loch, situated on the north side of the town, was originally an artificial creation forming part of its medieval defences and made expansion northwards difficult. The water was habitually polluted from sewage draining downhill from the Old Town.