Where do light dependent reactions of photosynthesis take place?

Light dependent reactions take place in the thylakoid (the Calvin's cycle, or the independent reaction, takes place in the stroma).

To get a picture of a thylakoid, bear with me:

First, you have a whole plant. Zooming in, you have a cross section of a leaf, made up of a few cells (called the mesophyll). Zooming in further, you have one plant cell. Inside this cell, you have chloroplasts. Inside the chloroplasts, you have stacks of discs called grana. Each disk in each granum is called a thylakoid.

The PSI and PSII are what use the light.