The two sides are connected both by a bridge over, and a tunnel (Duke Dog Alley) under, Interstate 81.[38] Other unique campus features include Newman Lake, a 9.7-acre (39,000 m2) body of water in the Lake Area next to Greek Row and Sonner Hall,[39] and the Edith J. Carrier Arboretum, a 125-acre urban botanical preserve in Harrisonburg and on campus. The arboretum combines naturalized botanical gardens (33 acres) and forest (92 acres), and is Virginia's only arboretum on a public university campus.