From a photo sleeve in the collection of the University of Maryland:
Exterior view of Enoch Pratt Free Library branch Clifton Branch. 18 recently completed, 2001 N. Wolfe St. c 1920, opened Nov 1916. 
From the Annual Report of the Enoch Pratt Free Library in 1917:
Branch No. 18 – Darley and Clifton Parks
The plans for this Branch Library having been drawn by the Architect, Mr. Otto G. Simonson, the contract for construction of the building was awarded in March to R. B. Mason. The lowest bidder of the heating was The Enterprise Steam and Hot Water Heating Co., and on wiring, the Kingsbury-Samuels Co. Construction of the building was begun about the beginning of April and was pushed without undue delay, so that the building was completed in the autumn, and after some four thousand volumes were placed on its shelves, the opening exercises occurred upon November 16. The building is of English scholastic architecture, built of red brick with limestone and terra cotta trimming. It has a slate roof. The interior is arranged in similar manner to the other Branches recently constructed for the Library. 
From a photographic collection at the Library of Congress:
The site was donated by Frank and Florence Novak in 1914. The branch was later erected in 1916 with funds given by Andrew Carnegie. 
1. There appears to have been extensive discussion  about closing the Clifton branch in 2001. The branch had the lowest circulation in the system, which faced a severe budget crisis.
2. Per the 1917 Annual Report , the day of lowest circulation was the library's opening day. In researching this series, I have found this to be atypical: usually opening days are amongst the busiest days for a library.
3. There is a "Clifton Station" post office in Zone 18 in Baltimore. The Library, however, is located in Zone 13, which is served by the Waverly Sranch. Thus, these covers were submitted to Waverly for their postmarks.