Question: Which building, a former schoolhouse, is part of a historic district in downtown Cincinnati, bounded by 3rd, 5th, Sycamore, Commercial Sq, and Butler Sts.
Context: The Charles O. Boynton House is located in the DeKalb County, Illinois, city of Sycamore.  The home is part of the Sycamore Historic District which was designated and listed on the National Register of Historic Places in May 1978.  The Queen Anne style mansion sits on a stretch of Sycamore's Main Street that is dotted with other significant Historic District structures including, the Townsend House and the Townsend Garage.  The Boynton House was designed by the same architect who designed the Ellwood House in nearby DeKalb and the David Syme House, another house in the Sycamore Historic District. Prospect Hill is a historic district located on a hillside outside of downtown Cincinnati, Ohio, United States.  It is part of the Mount Auburn neighborhood of Cincinnati.  Prospect Hill is bounded by the following streets, Liberty, Sycamore, Boal and Highland. Lytle Park Historic District is a historic district in Cincinnati, Ohio, United States.  Roughly bounded by 3rd, 5th, Sycamore, Commercial Sq., and Butler Sts.  in downtown Cincinnati, it centers on Lytle Park. Pleasureville Historic District is a national historic district located at Springettsbury Township in York County, Pennsylvania.  The district includes 105 contributing buildings and one contributing site in the crossroad community of Pleasureville.  Most of the buildings are residential include 19th century vernacular dwellings with notable examples of early 20th century Colonial Revival and Italianate style dwellings.  Notable non-residential buildings include a former schoolhouse (c. 1870), meeting hall (c. 1875), former store and accessory shop (c. 1860), and small industrial shop (c. 1930).  The contributing site is the Pleasureville Cemetery with 72 marked graves dating between 1865 and 1929. Guilford School is a historic former schoolhouse, now housing commercial offices, on the east side of Downtown Cincinnati at 421 E 4th Street.  The building is adjacent to Lytle Park is a contributing property to the Lytle Park Historic District. Woodwardville is a small, rural Unincorporated community situated in western Anne Arundel County, Maryland, containing 27 structures, 16 of which are historic and included in the Woodwardville Historic District, listed on the National Register of Historic Places in 2003.  Most of the structures are located adjacent to Patuxent Road, which runs through the center of the community.  On the north end of the district, a small street, 5th Avenue, runs west from Patuxent Road underneath the train tracks.  Prior to the establishment of what would be later known as Fort George G. Meade in 1917, the road once continued on to Laurel.  Three of the seven buildings along 5th Avenue are historic.  Woodwardville's building stock consists principally of late-19th and early-20th century domestic architecture.  Good examples of the Bungalow, Foursquare, Tudor Revival, and Queen Anne styles are present, as well as older traditional vernacular classifications such as the I-house.  These older forms are supplemented by a handful of post-World War II era structures.  Woodwardville also features several public or commercial buildings including a church, a former schoolhouse, the ruins of a store and storage or service buildings associated with the railroad.  Many of Woodwardvilles' older buildings fell into decline following World War II, but in recent years, due to its close proximity to commuter rail service, Woodwardville has evolved into a bedroom community for persons working in Washington, D.C. and Baltimore.  Investment by new residents resulted in the restoration and renovation of many buildings which had formerly been in deteriorating condition.  Despite the intense development a few miles away in Piney Orchard, this quaint community retains its ability to communicate its historic qualities and distinct sense of place. As of 2007 there are five church buildings in the Sycamore Historic District, located in Sycamore, Illinois, United States which are listed as contributing properties to the district.  The Sycamore Historic District was added to the U.S. National Register of Historic Places on May 2, 1978.  When it was nominated to join the National Register there were seven church buildings within the district.  One of those included is a residential structure that was utilized as a church when it was first constructed; the Arthur Stark House was once home to the Sycamore Universalist Church congregation.  In the time since its listing, two churches have been destroyed or demolished.  The Evangelical Church of St. John was destroyed by fire in 2004 and the United Methodist Church in Sycamore is no longer extant, replaced by a modern office building. Old Sycamore Hospital is two-story brick structure in downtown Sycamore, Illinois, United States.  It is a contributing structure within the Sycamore Historic District.  The district was established when it was added to the National Register of Historic Places in 1978.  The hospital building is located at the corner of Elm and Somonauk Streets in Sycamore. The Fernandina Beach Historic District is a U.S. historic district located in Fernandina Beach, Florida on Amelia Island.  The Fernandina Beach Historic District was included on the National Register on July 20, 1973, encompassing approximately 1,500 acres (610 ha), bounded by North 9th Street, Broome, Ash, South 5th Street, Date, and South 8th Street.  On April 20, 1987, the National Register listing was expanded to include an additional 970 acres (3.9 km²), bounded by Sixth, Broome, North 3rd, & Escambia Streets; Seventh & Date Streets, and Ash.  Approximately 300 buildings are included in this district. Hunter School is a historic building near Tabor, Iowa, United States.  The one-room schoolhouse was built in 1901.  The school was named for John H. Hunter, a farmer and landowner on whose property the original school was built in 1901.  Its use as a schoolhouse came to an end in 1920 when it was consolidated into the Tabor School District.  The building was used as a township meeting and a polling place until 1990.  Since then it has been maintained as a historical landmark.  The former schoolhouse is a frame structure built on a brick foundation, and consists of a 24 by main block and an 8 ft square bell tower-entrance.  While the schoolhouse overall follows a basic plan for a one-room schoolhouse, it departs from that plan with the asymmetrically placed corner tower.  It was added to the National Register of Historic Places in 2007.
Answer: Guilford School