Nathan Rd

Yes, it is Nathan Rd with Salisbury Rd on the right. The Time-Ball Tower on Signal Hill is in place. I reckon the photo was taken about 1910s from the former Marine Police HQ.

I think this picture is later c1925 and taken from the Kowloon Hotel. The large empty plot on the left of the photo includes K.I.L. 413 and has been cleared for building:

From the 1928 PWD Report 

In course of erection: - 

10 European houses (10 shops and 30 flats), on K.I.L. 407, Nathan Road.

Yes, you are right. In 1927, there was a large vacant plot of land behind the Kowloon Hotel.

MMIS refers:

A panoramic view of Kowloon shows Nathan Road in the foreground, lined with large, colonial-style 3-4 storey buildings. On the right, the Signal Hill (Blackhead Point) with the Signal Tower and the time-ball are prominent. The signal tower is without the dome (added in 1927). Below, Middle Road runs up...