The Time Tunnel of August Kaplan — Jane Shoup

It is strange and life-altering enough when almost thirteen year-old Kate Kaplan and her mom inherit a Chicago brownstone from a long deceased great-great-great uncle but in a hidden part of the basement, Kate discovers a locked room and a trap door that leads to a closed off tunnel ... except on rare occasions when the far ends opens to a time gone by when her triple great uncle August Kaplan lived.