For instructions on extracting multi-part archives, see this resource from Microsoft Q&A . How to Open and Extract .001 Files - Microsoft Q&A
The file ALEXANDRIA.7z.001 is the first part of a multi-volume archive, commonly containing large data dumps, web snapshots, or e-book collections. To extract the data, all parts must be downloaded and extracted together using software like 7-Zip, starting from the .001 file. ALEXANDRIA.7z.001 - BayFiles