Archaeologists have uncovered an Iron Age funeral site along the HS2 route.
The graves, at least 2,000 years old, show a settlement existed on the river bank site at Coleshill, near Solihull.
The cluster of several dozen sites, placed on funeral pyres, should shed a light on what people did with their dead, experts said.
It is one of a number of discoveries made by archaeologists ahead of construction work for the 225mph rail line.
Emma Carter, from Wessex Archaeology, told the Local Democracy Reporting Service experts were uncovering "tantalising" evidence from the past and an in-depth investigation of the graves would follow.
"[It] should offer some interesting ideas of what they do with their dead," she said.
Aside from the remains of the Iron Age settlement, the teams have also been investigating a Romano-British enclosure and will be carrying out research into where a Medieval manor house once stood.
During works, the archaeologists have uncovered Roman brooches, a serpent design from the Victorian era and a coin dating from the 1500s - during the reign of Queen Elizabeth I.