Construction of Heidelberg Castle began in the 13th century, and over the centuries, it evolved into a stunning mix of architectural styles, including Gothic, Renaissance, and Baroque elements. The castle complex boasts an imposing façade, decorative details, and picturesque towers, creating a breathtaking silhouette against the backdrop of the Neckar River valley. One of the most iconic features of the castle is the Heidelberg Tun, or "Großes Fass" in German, which is an enormous wine barrel housed within the castle's cellar. This massive wine barrel, with a capacity of around 220,000 liters, has become a famous symbol of the castle and serves as a testament to the region's wine-making heritage.

Constructed in the late 18th century, the Alte Brücke crosses the Neckar River and connects the old town of Heidelberg with the Neuenheim district. The bridge is characterized by its elegant stone arches, providing a stunning backdrop for the surrounding landscape. One of the most striking features of the Alte Brücke is the twin tower-like gates, known as the Brückentor or Bridge Gate, located at each end of the bridge. These gatehouses add to the bridge's architectural grandeur and have become iconic symbols of Heidelberg.

Built in the late 18th century, the Karlstor was part of the city's fortifications and formed one of the main entrances to Heidelberg. The gate features an elegant neoclassical design, characterized by its triangular pediment, Doric columns, and ornate detailing. One of the most captivating aspects of the Karlstor is the grand statues of Karl Theodor and Minerva, the Roman goddess of wisdom, adorning the gate's façade. These sculptures add a touch of elegance and historical significance to the structure.

Built in the late 18th century, the Studentenkarzer served as a place of confinement for university students who had committed various minor offenses, such as drunkenness, disorderly conduct, or engaging in duels. These students would be sent to the Studentenkarzer as a form of punishment. The prison itself is a captivating blend of history and folklore. The cells are adorned with graffiti, artwork, and inscriptions created by the incarcerated students, which offer a unique insight into their lives and experiences. These drawings and writings often contain humorous and witty anecdotes, adding a touch of whimsy to the otherwise austere environment.