Hilltop Cottage was built on Mountain Road in 1910 and still stands today as a private residence. This postcard view is from around 1920 and may have been taken by Charles Cassell.  There are room numbers on the bedrooms and the bath as if to designate them for summer renters. There were several homes in Thurmont where rooms could be rented for the weekend or longer. Thurmont was on the Western Maryland Railway and benefitted from the travelers that would come up from Baltimore to the cooler mountains during the summer months. The many hotels, rooming houses, and the amusement park at Pen Mar were big attractions at the turn of the 20th century. The Western Maryland Railway often ran two trains a day between Pen Mar and Baltimore to satisfy the demand. This house was purchased by Ross Lillard's grandfather and grandmother in 1919, but they did not rent rooms, However, they usually had a grandmother, uncle, other relatives, and their three daughters living with them.
My thanks to Ross Lillard for the details about Hilltop Cottage.