This 30 meters high rock hill was used as guard hill in the Middle Ages. If enemy ships were seen coming from the sea, fire was lighted to the hill to warn local people. After the great fire in Turku (1827), instruments and astronomical books of Turku University observatory were transferred to Helsinki.
The Helsinki astronomical observatory was built to the hill in 1834. It designed in cooperation by professor Friedrich Wilhelm Argelander and architect Carl Ludvig Engel. The observatory was among the most modern astronomical observatories of its time, and served as an example for several European observatories that were built afterwards. A separate tower was built in the observatory garden for the telescope designed for astrophotography. This building was finished in 1890.
At the top of the hill is is also situated Stigell’s monument Haaksirikkoiset (“shipwrecked”), erected in 1898. The sculpture is stretching to the west and increased the national spirit in the end of the 19th century.
Olargues is a good example of a French medieval town and rated as one of the most beautiful villages in France. It was occupied by the Romans, the Vandals and the Visigoths. At the end of the 11th century the Jaur valley came under the authority of the Château of the Viscount of Minerve. The following centuries saw a succession of wars and epidemics, and it was not until the 18th century that Olargues became re-established. This was due to the prosperity of local agriculture and artisanal industry.
The Pont du Diable, 'Devil's Bridge', is said to date back to 1202 and is reputed to be the scene of transactions between the people of Olargues and the devil. The old village is clustered around the belltower, which was formerly the main tower of the castle (Romanesque construction). The old shops have marble frontages and overhanging upper storeys. A museum of popular traditions and art is to be found in the stairs of the Commanderie.