Here is a feature called the Vallis Alpes, or Alpine Valley. It is a valley that bisects the Montes Alpes range and runs from Mare Imbrium to Mare Frigoris. This feature is over 80 miles in length and widens to almost 6 miles. While I have imaged this feature in the past, to date, this is the best resolution I have obtained.
Tech Specs: ZWO ASI290MC camera and Meade 12” LX90 telescope mounted on a Celestron CGEM-DX mount. Software used included Sharpcap v2.9, AutoStakkert! Alpha Version 2.3.0.21, ImagesPlus v5.75a, and Registax v6.1.0.8. Photographed on January 7, 2017 from Weatherly, Pennsylvania.