Jantar Mantar Observatory - India c1945

The Jantra Mantra (literally the 'instrument and formula' and often
called the Jantar Mantar), is located in the modern city of
New Delhi, Delhi.
It consists of 13 architectural astronomy instruments, built by
Maharaja Jai Singh II of Jaipur, from 1724 onwards and is one
of five built by him, as he was given by Mughal emperor
Muhammad Shah the task of revising the calendar and
astronomical tables.
There is plaque fixed on one of the structures in the Jantar Mantar
observatory in New Delhi that was placed there in 1910 mistakenly
dating the construction of the complex to the year 1710.
Later research, though, suggests 1724 as the actual year of
construction.
The primary purpose of the observatory was to compile
astronomical tables, and to predict the times and movements of
the sun, moon and planets.
Some of these purposes nowadays would be classified as
astronomy.
(info from Wikepedia)