Just looking at this gives me vertigo.
You may remember Mt. Lowe from a
previous post on Echo Mountain that showed a horse-drawn tram on a rather steep incline. You can read all about the Mt. Lowe Railway
here. This card shows the upper part of the railway, above the Mt. Lowe Incline on the way to the Alpine Tavern.
The railway was plagued with problems, and there's little trace of it anymore, but it must have been a fun trip for people who lived close enough to Pasadena to take the ride. Here's a card showing the Great Incline and the funicular that transported passengers up Echo Mountain.
Here are the backs of the cards in the same order. The first one was written on September 1, 1930 and mentions crossing 18 bridges besides this circular bridge.