The Trophy is hidden in one of the rooms on the upper level of the subway station #1 #2.
After reaching the area marked as the Trophy location, look up #1 and use the Ceiling Climb skill by pressing RB to stick onto the metal construction #2.
Head west, reaching the area where you will be able to climb onto the upper ledge by pressing A #1. Afterwards return east, thanks to which you will come across the secret you're looking for #2.
The Trophy you're looking for can be found above the locked gate dividing the tunnels from the main subway station #1, but luckily you don't need to call Batman for help. Instead, use the Ceiling Climb skill by pressing RB and collect the Trophy #2.
The trophy is below the balcony #1, so start off by jumping onto one of the balustrades #2.
Press the right trigger and A at the same time, which should result in Catwoman sticking onto the balcony #1. Now just approach and collect the Trophy #2.
The Trophy is hanging from the roof. Start off west #1 of its location and use the Ceiling Climb skill by press RB to stick onto the metal construction. Collect the secret #2.