Thought I'd write a quick mini-guide for how to do this since it's a common question. It's actually very simple.

First, you'll need to hit the subscribe button.

Next, open up TF2 and wait for the map to download. After that's done, make sure that you can open the developer console. In the game options, make sure "enable developer console" is checked. The default key is the tilda (~). For more info on how to do this, check out the TF2 wiki.

Enter this into the console:

Wait for the map to load, pick a team, and take a look around! That's it!

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You can do this with ANY map in the workshop. Let's look at the link for this map, cp_antiquity:

https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=960317656

Do you see the ID number, right at the end of the URL? Every map in the workshop has its own number. Copy that number, and just the number, of the map you'd like to explore.

Follow the instructions above (Subscribe, open the console, etc), but when you're ready to start up the map, instead you will do this, replacing <#mapnumber> with the number you copied.


Have fun exploring the workshop!