A man is still perched on the awning of a Chatswood apartment building, while the body of a young woman remains concealed by a tent in an alley below, more than 11 hours after it was discovered on Monday.

A pedestrian made the shocking discovery of the woman's body near Chatswood train station about 6.30am.

It is understood the woman, aged about 25, suffered injuries consistent with having fallen from a height.

At around 7am, police were called to attend an apartment building bordering the alley on Brown Street, where a young man was found kneeling on an awning above a top-floor balcony connected to the apartment complex gym.