In December 1797 the Haldane brothers set up a society, consisting of Christians from all denominations, under the name of ‘The Society for Propagating the Gospel at Home.’ Their sole intention was to make known the Evangelical Gospel of our Lord Jesus Christ. James Haldane spent his time between tours evangelising the villages around Edinburgh, speaking to large crowds on Calton Hill and spending a lot of time studying the Bible.
I do not know exactly where on Calton Hill Haldane spoke, but the area in front of the Column structure seems the most logical. If anyone can give me more information, please do.