The four face Brahma (Phra Phrom) statue located at Erawan Shrine was built back in 1956. It was built after series of bad mishap occurred during the construction of Erawan Hotel owned by the government.
You can buy offerings, joss stick and other praying items at numerous stalls located along the Ratchadamri Road.
Since after it was built, the construction of the Erawan Hotel went well. In 1987, the hotel was demolished and replaced with Grand Hyatt Erawan Hotel.