A Temple for Astronomy on Calton Hill

We arrived in Edinburgh on July 18, 2026. After checking in at the hotel, we went for a walk. Calton Hill was right behind our hotel. It's a bit of a climb, but from the top you get a great view over Edinburgh and the castle. On the hill stand the round tower of the Nelson Monument and the National Monument of Scotland, an unfinished copy of the Parthenon that only got its front row of columns before the money ran out. For us, though, the most interesting building on the hill was the old City Observatory.

Walking up Calton Hill. The City Dome is on the left, the Nelson Monument peeks out behind it, and the small dome of the Playfair Building is in the distance.

A Temple for Astronomy

The observatory is not one building but a small group of them, surrounded by a wall. You enter through a gate with "CITY OBSERVATORY" carved above it.

The two of us at the entrance of the City Observatory.

The main building is the Playfair Building, designed by William Henry Playfair and started in 1818. It looks like a small Greek temple, with columns on all four sides and a dome in the middle. In 1822 it became the Royal Observatory, until the astronomers moved to the darker and larger site on Blackford Hill in 1896.

The Playfair Building, with its small observatory dome on top.

Seen from the corner, the building is shaped like a cross, with a portico on every side.

In the corner of the site stands Observatory House, with its Gothic tower. This is the oldest part: James Craig started it in 1776, but the money ran out after the first tower. In the other corner is the City Dome, with its green copper roof, added at the end of the 19th century.

Observatory House, the oldest building on the site (1776).

The City Dome.

The Transit Telescope

The highlight for us was inside the Playfair Building: the old transit telescope. This kind of telescope can only move up and down along the meridian. By timing exactly when a star crosses the meridian, astronomers could set their clocks very accurately. The lens was made by Fraunhofer, and after his death Repsold, and later his son, finished the instrument. It was installed in 1831.

The telescope rests between two heavy piers, and an opening in the roof lets the observer see the sky along the meridian. Behind it stands a long-case clock. The time measured here was used for the time ball on top of the Nelson Monument, which dropped every day so ships in the harbour of Leith could check their chronometers.

The pier carries the axis of the telescope.

What I liked most was the reclining observing chair in front of the telescope. As an observer, I know how uncomfortable it is to look through an eyepiece near the zenith. The astronomers here clearly had the same problem.

The reclining observing chair, made for objects high in the sky.

Visiting

Today the buildings are home to the Collective Gallery, a gallery for contemporary art, and there is a café on the site. The transit room is open to visitors, and entrance is free. [Optional: add a line here if you want: how long you stayed, the view from the wall, the weather, what you would recommend to other astronomers visiting Edinburgh.]

If you are in Edinburgh, the walk up Calton Hill is worth it, even if you aren't into astronomy. If you are, the old transit telescope is something you shouldn't miss.