The words opposite and across from mean that something is located at the other side of something.

The bank is opposite the post office. or The bank is across from the post office.

Henry sat opposite me at the table. or Henry sat across from me at the table.

The expression in front of simply means that one thing is closer to a point of reference (the "front" of an area, or the point of view of the person looking).

I stood in front of the bank.

He sat in front of me in the classroom.

The word before can be used for location/position, but it is somewhat rare and more formal. Instead, before is typically used for time or for position in a sequence:

We need to pack our bags before leaving for the airport.

The letter i comes before the letter e in the word "friend." or position in a sequence

100 Places to visit in India

Jaisalmer Fort

Located in the city of Jaisalmer in Rajasthan is the Jaisalmer Fort, one of the largest forts in the world. The fort sits as a symbol of pride amidst the beautiful golden sands of the Thar Desert. There are quite a few Jain temples within the forts premises, apart from a Royal Palace, massive gateways and other highlights. The best way to visit the fort is to take a safari atop a beautifully decorated camel or elephant. In fact, a visit to Jaisalmer isnt complete without a quintessential desert safari atop a camel.