Most of the sights are within walking distance of each other, but visitors can also take public transportation like buses or trams. A single ticket for the entire network costs 2.50 EUR and is valid for 1 hour. Taxis are also available but can be much more expensive, costing around 15-20 EUR for a short ride.
If you have more time, consider taking a boat tour on the Neckar River, exploring the University Library or visiting the Karl Theodor Bridge. If you have less time, consider skipping the Philosopher's Walk or only visiting Heidelberg Castle and the Old Bridge.
Heidelberg is primarily served by the Frankfurt Airport, which is the largest airport in Germany and located approximately 80 km north of Heidelberg. The airport code is FRA. Travelers can use trains, buses or taxis to get to the city center which takes around 1-2 hours, depending on the mode of transportation.