Making Maps

Total Newbie to Roll20, but very long term gm. I have gone through a number of tutorials and videos but none of them have addressed this (so far at least).   I am trying to create maps inside a test campaign of mine to get the hang of it. When dragging and dropping items onto my map (and it doesn't matter whether its a freebie or one of my Marketplace purchases) the items, even though they may be large buildings, show up miniaturized to a 1x1 square. I can stretch it out, but I did not see this happening on any of the videos I watched - on the videos they always open up full sized. Am I doing something wrong? Should I have to stretch the items?

There are a few things you can do: 1) Drag images in with Alt held down should retain it's original size. 2) Turn off the grid and things should come in at their original size 3) If you know the size of what you're dragging in, and you're doing many of them at the same size, you can set the grid to be that size and it will scale them all to that size. Note that the original size of an image is not necessarily the best size for using it in Roll20.  The square grid is 70px by 70px.  If you have a map that was created with a grid of 100px by 100px, it's not going to line up well at actual size.  You'll need to resize it to align with the built in grid, or remove the grid from Roll20, or whatever you desire.  Just something to be aware of. Look up the Align to Grid Tool, and the Advanced right click options for graphics for setting their size either in pixels or grid units.

To add to the above, dropping them onto the map layer rather than the objects layer (which will always default to 1x1) can help retain dimensions too.

Some of us Marketplace Artists put the size dimensions into the name of the file like: Hall_Corner_4x4 So that people know to set their tiles up in roll20 at 4x4 units.  Not everyone does this however.

Thanks to you all, I think I have it down now.  Another question though, the sizes (under 'set dimensions') of the items defaults to pixels. Is there any way to change the default to 'units' instead of pixels? - I know I can manually change each item indivually, but I prefer working in units.