My newest discovery is the abandoned and historic Little Manatee River Railroad Bridge that was built by the Seaboard Air Line Railway somewhere around 1902-1913. It was decommissioned and abandoned around 1986. This is located in Hillsborough County Florida.
Seaboard Air Line Railway was created in the 1880s by the consolidation of the Seaboard and Roanoke Railroad, which dated back to the earliest decades of American railroads, and other lines in the Carolinas into a single system. Eventually, over 100 lines would be incorporated into the SAL.
See many more photos on my website: http://www.trailviewmount.com/