6th October 1992 marked the opening of the Onassis Cardiac Surgery Centre in Athens, Greece. 30 years later, the Onassis Foundation has completed an extension to the hospital as per the original design by Llewelyn Davies.

The hospital was built as a memorial to the eldest son of Aristotle Onassis and donated to the Greek government. It became the first certified hospital in Greece for the development and provision of health services in the field of heart transplant, heart surgery and cardiology for both adults and children.

Capable of holding 110 beds, the hospital features intensive care units, semi-intensive care units, heart-attack therapy, haemodynamic laboratories, paediatric heart surgery unit, cardiac surgery unit, cardiology unit, electrophysiology and pacemaker laboratory, as well as an outpatient department, diagnostic department and clinical laboratories.

The hospital was designed to reflect modern standards of its time but to also allow for flexibility in future healthcare ideas. The building has allowed for new equipment and services that have prolonged the OSCS as one of the leading hospitals in Europe. According to the Onassis Foundation, the survival of heart transplants reached 94% during its first year and 70% across the decade, some of the highest percentages internationally.

From the second floor to the sixth, each floor is set back with terraces, giving a ziggurat-like character to the architecture. The extension allows for this language to continue with further colonnades over the piazza, as the upper floors are set back in a similar manner to create a second ziggurat-like structure, linked together by a glazed bridge.

Close to the port of Piraeus, the OCSC still remains a key architectural landmark across the Athens skyline, with its stepped massing and deep horizontal reveals noticeable, while retaining a similar white marble stone against the local urban vernacular. The high quality of the materials is noticeable even today as it appears as original as it was 30 years ago.