This question is difficult to answer because unfortunately, there were no details about his marking behavior provided. I don’t know if it’s truly a marking problem; nonetheless, as with all housetraining problems, you need to approach your dog’s situation just as you would a young, un-housetrained puppy. So please read the Housetraining Handout thoroughly, then get started on the program!
If it truly is marking, there are a few things that you can do along with the plan outlined on the handout. First, I’m assuming your dog is male; there are female dogs who territorially mark as well. If your dog is male and isn’t already neutered, have that done.
When you feed him, put his food in as many bowls as you can find; add just a bit of food in each bowl and place them everywhere he’s marked. Do this for at least a month. Does he mark after another dog has visited your home? If so, have the dogs play outside so he doesn’t feel the need to re-establish your home as his territory.
Is he marking near the front door after the UPS delivery person stops by? Or is he marking in any other situation where your dog feels his territory’s being invaded? If so, find a great way to change the marking to a good behavior, like going to his bed and waiting for you to release him. Teach him the “Go to Bed” command so he learns that it’s not his job to guard the front door.
You mentioned that he marks “all over the place;” is there a particular thing that triggers this behavior? Does it happen when guests are over, or when there’s construction going on nearby? Or does it happen when a dog just walked by the house? The next free day you have, try to ascertain any possible triggers by really paying attention to nearby sounds and activities. If you find any triggers, take him for a number of brief walks throughout the day each time you hear or think he hears some kind of activity near the house. Also, make sure your dog gets at least one hour of exercise every day; it’s much easier to train a calm dog!
Use the tips in both handouts I’ve mentioned and use positive reinforcement in your program. If you still need assistance after a few weeks, you’d greatly benefit from hiring a professional dog trainer or behavior consultant to come to your house to help you. A great place to start your trainer search is with American Pet Dog Trainers. Just click on “Trainer Search” and then type in your zip code – a list of nearby trainers will come up. Make sure to call at least three to five people before deciding on a trainer, and be sure the trainer is clear on the methods he or she uses; positive reinforcement and motivational techniques help build a wonderful relationship with your dog.