echiromani:SolareThis obelisk is one of two that were erected at the temple of Heliopolis by Psamtik
echiromani:SolareThis obelisk is one of two that were erected at the temple of Heliopolis by Psamtik II (c. 590 BC). It had probably been thrown down by Persian invaders in 525 BC when Augustus had it brought to Rome in with the Flaminio obelisk in 10 BC. It derives its name, Solare, from the purpose which it served: the gnomon of a sundial on the Campus Martius. It was found in the 16th century but reburied. It was yet again rediscovered and erected by Pope Pius VI in front of the Palazzo Montecitorio in 1792. -- source link