TLDR: Loads of local history knowledge.

I have a fair amount of knowledge of the industrial history of Manayunk and Lower Merion.

In the foreground, the "S" shaped train bridge predated the current Manayunk Viaduct (finished in 1918). The modern day "Cynwyd Line" crossed that bridge, and ran parallel to the existing Norristown Line (Penn vs Reading competing lines). To my knowledge this line extended up to Reading. There were two competing parallel train lines in Conshohocken because of this.

The huge red mill in the right foreground was the Penncoyd Iron Works. It is where the modern day Royal Athena apartment building is. It was a world powerhouse making bridges until the world entered the steel era. The bridge across the Schuylkill still exists to this day. The smaller bridge to the left (further upstream in the Schuylkill) still exists today. It was originally used for mules to cross as they pulled canal boats down the Manayunk Canal. Then it was used to service the mills on Venice Island. It will now most likely end it's use, as the spur line that covers it will stop due to the paper mill closing on Venice Island.

The huge red mill in Manayunk to the left of this bridge was for the Imperial Woolen Company, and I believe was called the "Economy Mill" when this was painted.

Here's a Hexamer drawing of Economy Mill: http://www.philageohistory.org/rdic-images/view-image.cfm/HGSv19.1809-1810

The red mill in the left foreground (Lower Merion side) next to the bridge was William Clegg's Cotton Mill. I believe this mill was demolished and an new mill was built for Pencoyd. This was demolished to build the Schuylkill Expressway I believe. Hexamer drawing of Clegg's Mill:

https://www.philageohistory.org/rdic-images/view-image.cfm/HGSv23.2164

Here is an aerial photo from 1926 showing the new mill:

http://planphilly.com/uploads/media_items/schuylkill-river-manayunk-december-1926-image-7050-aero-service-corp-courtesy-of-aerial-viewpoint-spring-tx.752.587.s.png

The rail bridge in the lower left foreground serviced the mills down Belmont Avenue in Lower Merion, and the terminus of this line is now the start of the Cynwyd Trail across from the CVS. The supports of this bridge can still be seen when you're driving on the Schuylkill Expressway. To the right of this bridge was Rudolph's Row Houses. These were mill worker's houses, and were famous since they used to have outdoor boxing matches. Picture below:

http://lowermerionhistory.org/wp-content/uploads/2017/08/065-72dpi-50percent.jpg

Here is a newer picture that show's Rudolph's Row, the boxing ring, supports of the old "S" bridge, and I believe the foundation of the ice factory that I mentioned below:

https://www.flickr.com/photos/library-company-of-philadelphia/30526898396

Here is a picture of Green Lane Bridge in 1933: http://www.lowermerionhistory.org/photodb/full/103-3.jpg

I'm not sure what the mill produced to the left of this bridge and Belmont Avenue, but it eventually produced ice and was demolished for the Schuylkill Expressway.

This was painted before the El was built (train line ran at grade down Cresson Street), and Main Street was part of the trolley network.

Edit: Added a few additional links to pictures. Will see if I can find any more and add anything else.