The Old Royal High School is a historic building located on Regent Road in the city of Edinburgh, Scotland. It was designed in the Greek Revival style by architect Thomas Hamilton and completed in 1829. The building was originally intended to be used as the Royal High School of Edinburgh, but it was never actually used for this purpose.

The building features a grand entrance portico supported by Corinthian columns, which is one of the most prominent features of the building's design. The interior of the building features a large central hall with a dome ceiling, which was intended to serve as the school's assembly hall. The building also includes a number of smaller classrooms and offices, which were designed to be used by the school's teachers and administrators.

Over the years, the building has been used for a number of different purposes. It was briefly used as a temporary home for the Scottish Parliament in the 1970s, and has also been used as a music school and an arts center. In recent years, there have been a number of proposals to turn the building into a hotel or luxury apartments, but none of these plans have come to fruition.

Today, the Old Royal High School is a Category A listed building, which means that it is considered to be of national importance and is protected by law. It remains one of the most iconic buildings in Edinburgh, and is a popular destination for visitors to the city who are interested in its rich architectural heritage.