Following the Marble (Theatre) Street to the south, the ancient visitors and the modern-era tourists arrive at the very heart of Ephesus, known as Triodos Square. Even today, the moment when one enters the square can take the breath away. To the west, the magnificent facade of the Celsus Library towers over the space. Moreover, previously hidden from the view, the Curetes Street leading to the Upper City becomes visible. To the east, the colonnades gently made a curve and helped to hide the structures behind, a large peristyle villa and a public latrine.

The name of the square, Triodos, means "Three Roads", as it marked the crossroads of Curetes, Marble, and Ortygia Roads. In this place the road leading to Ortygia, a sacred groove, believed to be the birthplace of Artemis, started. Initially, the Gate of Mazeus and Mithridates was erected in the role of the Triodos Gate, at the junction where the Via Sacra to the legendary birthplace of the city's patron deity started. When this section of Ephesus was remodelled, the beginning of the Ortygia Road was moved up the slope to the south and marked with the new Triodos Gate, set at a different angle from the orientation of the three crossing streets.

The new Triodos Gate is now frequently called the Hadrian's Gate. Once, it had three storeys, of which only the lowest one has been preserved. Three openings led through the gate, and the middle one was the widest, with an arched vault. The side openings are still topped by architraves. The whole structure resembled the Arch of Hadrian in Athens and was thus dubbed the Gate of Hadrian. The building was restored after an earthquake of 262 CE, and water basins were added to its sides.

However, the gate was probably erected earlier, during the reign of Emperor Trajan, most likely as a triumphal monument. Its great dimensions suggest that it may also have been used for religious and ceremonial purposes. This assumption is strengthened by the gate's specific location. At the junction marked by the gate, a statue of Artemis once stood. Its fate is recorded in the inscription found nearby that stated that a person called Demeas tore it down as the image of "demon Artemis". He replaced it with a cross, the symbol of Jesus Christ. This event happened sometime in the early Christian era.

Nowadays, the gate, one of the most excellent examples of the sumptuous marble carving of the period of Trajan and Hadrian, marks the location of the entry to the Terrace Houses. The gate's partial restoration was carried out between 1986 and 1990 by the Austrian Institute of Archaeology, again financed by Anton Kallinger-Prskawetz.

Just to the right of the Hadrian's Gate, another important monument was situated. It was an altar dating back to the early imperial period. Its exact function remains the subject of the scholarly debate. The visible remains consist of a broad stairway that connects the U-shaped loggia with the Triodos Square. Peter Scherrer suggested that it was once the foundation of the so-called Parthian Monument, later reused for the pool in front of the Celsus Library. However, Friedmund Hueber proposed that this open structure could serve the jurisdiction purposes. In this case, the stairs could function as seats for the audience following the court proceedings. Finally, Dieter Knibbe concentrated on the sacred function of the area and suggested that the structure was the altar to Artemis. If the structure was decorated with the Parthian Monument, it could be seen as a memorial to Emperor Lucius Verus with respect to the city's chief deity.

The traces of a structure erected on the circular plan, to the right of the Gate of Mazaeus and Mithridates and opposite the Hadrian's (Triodos) Gate, belong to the so-called Circular Monument with a Fountain. It stood in front of the southern end of the Hall of Nero. Some researchers such as Hueber believe that this building, formerly a six-columned monopteros with Corinthian capitals and a conical roof, was the horologion, relocated here from the Commercial Agora. Other scholars, for instance, Scherrer state that it was a decorative fountain, beautifully contrasting with the simple façade of the Hall of Nero behind it.

This text is a fragment of a guidebook to Ephesus: "The Secrets of Ephesus".