The new observatory, whose construction could begin in 1739 and which was completed in 1741, was located inside the city, at Svartbäcksgatan.
The architect of the building was none other than the famous superintendent C. Hårleman.
Its tower superstructure, which rose high above the surrounding houses, formed for a whole century,
as can be seen from older Uppsala pictures, a characteristic feature of the city's silhouette.
The house is still there, although without the tower superstructure.
It is the so-called Oratio obliqua (Svartbäcksgatan 9 B), easily recognizable by its oblique position in relation to the street line.
The instrumentation, for whose acquisition Celsius had made great efforts and even released significant additions of his own funds, was for his time quite good.
These included a 12-foot sector by Sisson, a 5-foot passage instrument, various tubes and a fine
astronomical pendulum clock with
mercury compensation, which Celsius had made by the most famous watchmaker of the time G. Graham in London.
As a curiosity, it can be mentioned that the Grahams pendulum clock is still in progress to this day, albeit
after a restoration carried out by Kessel, at the Uppsala Observatory. And is doing well.
Through several donations, including Celsius' own precious collection of books, the observatory was gradually provided with a stately library.
Extensive observational work was carried out by Celsius himself (he died as early as 1744) and by contemporary and
subsequent Uppsala astronomers, and Sweden's contribution to astronomical research at the time was by no means insignificant.
Long and significant series of meteorological observations were also performed.