This map of Alexandria comes from E M Forster's Guide to Alexandria (1922).
The island of Pharos was, according to Forster, empty in the early days of Alexandria (possibly until the building of the lighthouse about 279 BC) except for a temple to Hephaestion. Presumably this temple is the one Cleomenes, the Greek Alexander left in charge of Egypt, built in the hope that Alexander would excuse his corruption charges. He was executed by Ptolemy in about 322 BC.
It is possible that the temple to Hephaestion might have been the first building that anyone saw on sailing into the new Alexandria. The prehistoric harbour (the island was known to Homer), might still have been in use until the causeway was built, creating the two great harbours, and merchants arriving in the new city might have drawn up their contracts and sworn to uphold them in Hephaestion's temple, as Alexander ordered that merchants' contract were to include Hephaestion's name, and oaths were sworn in Hephaestion's name.
Is this a testimony to Hephaestion's organisational abilities, and perhaps a reputation for fair dealing?