a farm in bolsena, italy.

this is a 1 hour, 20 minutes exposure. but since an exposure that long in a digital camera will produce too much noise, I shot 33 photos each exposed for 2 minutes, 30 seconds and then combined them all in photoshop to reduce the noise. I used a timer device set to bulb exposure to trigger the camera every 151 seconds for 150 seconds exposures.

update: thanks for overlay correction about handhled! yes this was shot on a tripod.
as for the photoshop question when you have multiple photos, you can drag all of them into layers above one them and change the layer tranfer mode of all the layers above the main layer to lighten.