What do you want from the climb?
For architectural history and views from the castle area, the castle is the natural choice. The old town lies below it, making the two a coherent day. Check your intended visiting scope, access and transport options first. Taking transport uphill does not mean that every part of the castle grounds is free of further walking or steps.
The Philosophenweg on the opposite side provides a different view of the town and castle. It is a hillside route, not a flat substitute for visiting the castle. If the panorama matters more than an interior, this may be your preferred focus. Plan the actual approach and return rather than merely saving a viewpoint on the map.
A day without a hillside programme
Heidelberg can also be enjoyed without a substantial ascent. Combine part of the old town with the Old Bridge and a Neckar walk. Crossing the river changes your perspective on the buildings without obliging you to continue uphill to the Philosophenweg.
The Neckar meadow can provide a break when weather and ground conditions suit. Give it a role of its own rather than treating it as leftover space after several hours of sightseeing. In wet or cold weather, a café can serve the same purpose: sit down, reconsider the route and choose the next section afterwards.
Limit the old-town loop
Hauptstraße can act as your orientation line. Side streets and squares introduce variety, but every additional loop lengthens the outing. Choose a point where you will turn towards the bridge or castle. This avoids walking the same long street repeatedly because a reservation waits at the opposite end.
Arriving with luggage is a reason to visit your accommodation before beginning the hillside programme. Cobbles, gradients and steps do not become easy simply because a suitcase is small. A light daypack leaves both hands available and remains useful even on a shorter urban walk.
A viewpoint is not a weather guarantee
Poor visibility reduces the appeal of a panorama. Keep an alternative in town and assess conditions in the morning. Equally, a clear morning may justify going to the viewpoint first and moving a flexible central section to later in the day.
For departure, do not treat the railway station and old town as the same place. Check which station your train uses and plan the connection from your final activity. A long descent followed by luggage collection needs more time than the distance in kilometres alone might suggest.
