Castlereagh Street at Hunter, 1900 to 1928

In 1900, below, the large building in the background is the Australia Hotel, which made way for Seidler's MLC Centre in 1972. Here, Martin Place hasn't yet been put through (it was finally finished in the 1930s.)

In 1922, density was increasing. Below, the fellow in the white helmet is a policeman, probably directing traffic as Castlereagh Street was then one-way northbound (until the Eastern Distributor was put through in the 1990s, when its direction was reversed as part of the wider new traffic system.)

You have just got to click on that pic for the original, the detail is incredible. 

By 1928, the city's urban density had consolidated. The little building on the right is still there for the moment, yet the building to its right has had more storeys added.