The area, which is near Park Street, was cordoned off by West Midlands Police after the discovery was made on Sunday, May 9.
The remains were found near the new Curzon Street HS2 station in Birmingham city centre.
Part of a pavement in the Park Street area was sealed off just before 10.30am, on Sunday, May 9, as officers examined the scene.
A spokesman for West Midlands Police said: "We are investigating after human remains were found.
"It is believed the remains have been at the location for some time.
"Tests are being carried out to identify the victim and establish the cause of death.
"Anyone with information is urged to contact West Midlands Police, quoting log number 1177 of May 9."