Hillhouse Avenue Historic District The Hillhouse Avenue Historic District encompasses the most complete and best preserved contiguous array of high style nineteenth and early twentieth century suburban villa architecture surviving in the City of New Haven. The district also ranks as one of finest extant examples of its type in the State of Connecticut. A high proportion of the buildings included within the district stand as examples of the work of nationally and locally renowned architects. The district’s development was both conceived and initiated under the auspices of James Hillhouse, one of the most prominent civic leaders and urban developers in late eighteenth, early nineteenth century New Haven.