I've been practicing with selection tools in Photoshop. The exterior of our library has changed only sightly in 100 years so it was a natural to choose to composite an old postcard and recent photo. I chose the area around the old entrance because that was a feature that had changed.
The perspective was different so I need to distort the selection area to match up the roof line. It's not perfect but taught me a bit about the tools. Here is the sequence: