The whitewashed walls of the old San Diego fort stand as a testament to Acapulco's status as a long-standing port city and date back to the Spanish colonial era. It's also one of the city's best vantage points for a panoramic harbor view; plus, there's an interesting local art and history museum housed inside.
The fort was actually built in 1617, but was partly destroyed in 1776 by an earthquake. When it was rebuilt, the Spanish added a moat (without gators in it--darn!)
It cost us about $1.50 to go into the museum, which wasn't bad for a pretty cool little place. A series of exhibit rooms focused on different time periods in Acapulco's history, starting from pre-colonial days and finishing with fairly recent times. It's not a huge museum, but they don't charge an arm and a leg to get in either . . .
The fort is located on a hill overlooking the harbor near the big port facility where the cargo ships and cruise ships dock. It's right on Costera Aleman--the city's main drag and is reached by climbing 80-gazillion steps (I counted). If you're lazy, take a taxi--they go in the back way and wind through the neighborhood on the backside of the hill. You'll probably need less rest under the trees than I did . . . whew!