The pic linked by ragdall at 26 Dec 06 - 05:18 AM is similar.

The horseback heroes statues are present which puts that pic later(?) than Sorcha's.

There are also rails for the horsedrawn trolleys which were not in hers.

A different style of street lamps is shown.

Ragdalls pic might be dated at least roughly based on years when the horsedrawn streetcars (on rails) were used at the opera house location. If that's of interest, the Vienna Streetcar Museum might be able to provide dates:

"In the former Erdberg streetcar depot of the Vienna Transit System, more than 80 historical Vienna streetcars - from an 1871 horse-drawn trolley to the first of the semi-automatic trains of the 1950s - are on display on more than a mile of track."

(There appears to be an address for the museum at that page, but I'd have to have a translator.)

John