And this is what UNESCO wrote in its 2006 report (whc.unesco.org/archive/2006/mis356-2006.pdf) on the World Heritage Site Istanbul:

"[A]n extension to the Four Seasons Hotel over the archaeological remains of part of the
Great Palace of the Roman and Byzantine empires is planned as a result of downgrading
protection from an “archaeological park” to an “urban and archaeological site” in the
new “Development for Conservation Plan” [...]

The Great Palace of the Byzantine Emperors occupies a wide area on the eastern end of the Historic Peninsula. Its history dates back to 196 A.D., when Septimius Severus started to rebuild the ruined city, and after the 3rd century it became the centre of civic life - the main palace of Septimius Severus, enlarged continuously in later
centuries and known as the “Great Palace”. Following damage during the Fourth Crusade of 1204, the palace was only used for occasional ceremonial functions and the remains slowly disappeared until in the 19th century the area was used for new buildings, like the “Halls of Justice,” a building erected 1854 by Gaspare Fossati
to serve as the university (Darülfünun) and turned into the law court in 1908 (destroyed by fire in 1933). The
need for a penitentiary led to the building of the prison in 1917/18, which continued in use until 1982. As

a joint venture between Four Seasons Hotels and Resorts and Enternasyonal Tourism Investment Inc. from
1994 the building has been transformed into the “Four Seasons Hotel” the project design and implementation
being signed by the architect Yalcin Özüekren. The whole area had been declared an “archaeological site” and
excavated under the supervision of the Istanbul Archaeology Museum. The former prison building is situated
either on the place of the former Chalke Palace or the Senate Palace. Excavation works within the area have
revealed foundations, passages and traces of frescoes from the 4th century A.D.

The new “Development for Conservation Plan” changed the status of the area from an “archaeological park”
into an “urban and archaeological site” – a status which allows new constructions within the area. A new
project signed by the same architect Yalcin Özüekren to build extensions to the Four Seasons Hotel has been
recently approved by the Protection Board. The mission visited the archaeological area including the Four
Seasons Hotel and the excavations on the north-eastern part. Architect Özüekren presented the conception
of his project on the extensions by maps and the design for the three new wings of the hotel: each of them is
planned on four pylons to be intruded in the ground, the ground floor being free and thus the excavation area
accessible for visitors.

As the extension project has been approved and the implementation is under preparation the mission members
expressed their concern over the following issues:

- the excavation works in the area which are not finished and the archaeological conservation works not yet
started;
- the pylons might be placed “outside” the archaeological relics, but for the working site for the extension
constructions seems to be insufficient, especially for ensuring the protection of the archaeological
remains.
- the project main façade on Kutlugün street, should prioritise and conserve the original architecture of the
remaining walls and avoid any intervention which might compromise its authenticity.
The mission therefore recommends that an impact study should be undertaken on the feasibility fo the
intervention, including international expertise."