Neckargemünd is a small town on the Neckar river, about 12 kilometres upstream from Heidelberg. It sits at the confluence of the Neckar and the smaller Elsenz river, in a wooded valley that feels surprisingly rural given how close you are to the Heidelberg-Mannheim urban area. The old town is compact and well-preserved, with half-timbered houses, a Gothic church, and a couple of pleasant squares where you can sit with a coffee and watch the boats pass.
The easiest and most enjoyable way to arrive is by river boat from Heidelberg — the upstream trip takes about two hours and follows a beautiful stretch of the Neckar past wooded hillsides and the ruins of several castles. The S-Bahn (line S5) from Heidelberg takes about 15 minutes for the return.
Neckargemünd makes a good starting point for walks along the Neckar valley. The Burgenweg (castle trail) passes through and connects several ruined hilltop castles in the surrounding forests. The Hollmuth ruins above the town offer a good view over the valley. About 5 kilometres away, the hilltop village of Dilsberg has a well-preserved medieval castle with a 78-metre tunnel system, excellent valley views, and a connection to Mark Twain, who wrote about it in A Tramp Abroad. For a longer outing, you can walk or cycle the river path downstream to Heidelberg — a flat, scenic route of about an hour on foot.