Rising damp, ground floor walls
Concrete will absorb water much like a sponge.  Assuming there is drainage at all, it's likely porous clay-pipe (that's why they call PVC drain pipes "drain-tile".)  This was often installed right up against the building.

Over time, when the ground shifts or roots get into the pipe, it breaks and clogs and no longer drains away.  What's left of it now draws water in towards the house and up against your concrete.  If you have gutters and downspouts that go into the ground, they connect into this system and basically seep into the ground around your house.  If you ever dig holes and find pieces of clay pipe, that's your drainage system.

There's really no fixing old clay drainage tile once it's shot.  You should get a contractor to give you estimates on drainage.  In my area, these companies also do landscaping.  Expect the cost to be in the thousands.