I took Aesop outside a few times randomly over the past few months. Each time he howled at the door the next day and I didn't want to encourage this so it never became a routine. I was off work for four days recently(which is kind of rare) and took him out each day. I put his harness and leash on and into his carrier to take him out. He had a blast and made it farther from his carrier each day. The next time I had to work and couldn't take him out at the time I had before he began howling at the front door immediately when I got home. Again, I didn't want to encourage this behavior and did not take him out. This is the fourth day and he continues to howl from the moment I get home. I have tried playing regularly and he seems uninterested for the most part or he will play and seem tired but shortly after, the howling begins. I know they like a routine or specific schedule but sometimes this just is not possible. I live in an apartment in a city on a kind of busy road. He doesn't seem to mind the traffic much but this means there is not option of us building any enclosure or something which is what I have read to be the best option. I do open the window for him which he has a perch to lounge. He seems less interested since going out so many times in a row. I am asking for any advice. Should I just stop taking him out since he doesn't understand it's not up to him when he gets to go? Should I wait until he stops howling everyday and make a set time to take him out?

Sounds like you've created a monster
I was thinking about taking Bryan out for the occasional walk in the park on a leash until I read Sherry's posts about Raiden demanding his twice daily walks come rain, hail, sunshine or snow!
I quickly decided that what he doesn't know won't hurt him ie if I never take him outside he won't know what he's missing!
My husband, in his "wisdom" decided to let Bryan out in the garden yesterday because he thought it would be nice. Bryan took off like grease lightning straight down the driveway towards the busy road! I nearly had a heart attack I managed to catch him before anything heinous happened. I put Bryan back inside at which point he very loudly protested for about 10 minutes over the indignity of being so rudely returned to his "captivity".
Needless to say, said husband will not be letting Bryan out ever again!

Aesop obviously really likes going outside!

I would suggest that you take him out when you can, but then invest in some ear plugs for those days when you can't. Or at least don't acknowledge his howling in any way - if you react to the howling he'll start to think that the howling is working, which will make him howl more.

Obviously letting him out on his own on a busy street in the city would be a non-starter - he'll end up dead/missing/injured.

I had this with my previous boy, I decided I wanted him to be an indoor cat and take him for walks on his harness, this worked really well and he loved his walks and nothing worried him.
We would drive to a quieter area than where I live and walk for around 2 hours and that kept him happy, we also sometimes just walked around the block and up the back lanes.
I found though once you start taking them out they get a real taste for it and cry at the door until you give in and take them out.
This time round I decided not to take the two I have now out, they are strictly indoor cats with lots of toys, what they don't have they don't miss.

_________________
Clare
Magic (brown spotted boy born 31 March 2012)
Pearl (seal Lynx Point girl born 1 October 2015)
Bristol, UK

Cats do love the outside. Every morning my kitties wait patiently for me to get up. If I don't get up as early as they like, the start chirping and moaning to let me know they are waiting. They scurry around me as I get dressed and head for the kitchen and wait by the door for me to let them out onto the screened in patio. It is spring and there are babies everywhere. I keep hearing a creature near the patio door that I can't identify or see. Grace is vigilantly standing guard out there and gets very excited from time to time. Aside from food, it is clearly the highlight of their days.

Oh gosh, I'm the expert here! LOL. I got my bengal when he was six years old and the owner allowed him to roam free. When I got him, he had just been in a bad cat fight and the owner gave him to me. I decided to conserve the rest of his nine lives and make him an indoor cat. Ha ha ha! He yowled 24/7. We could not sleep at night. My husband decided to build a large 12'x12' enclosure on our deck, which we did. We figured that would stop the yowling. Nope! Raiden loved the enclosure but wanted to go wandering outside. He was at the front and back doors constantly. So, I bought a harness and leash. My husband said he would never take to it, but he took to it immediately and out the door we went. I was working at the time, so he got an afternoon walk when I got home. On the weekend, he got two. Now I'm retired and he gets two walks a day. But he yowls until he goes outside. Once our eyes open in the morning, he starts. It takes me at least 30 minutes to wake up, get dressed, eat, get the bird feeders out. He yowls the entire time. Once we return, he settles down, but by 1 p.m., he is howling again. I take him out around two, so an hour of this, every single day.

Once a cat smells the outside world, it is never the same for them. You will never train him to accept going outside on your terms. It will be his terms or nothing. Thus a cat is either an indoor cat or indoor/outdoor cat. Your kitty will probably still love an enclosure, especially if it is on grass (our enclosure is on our deck and elevated). If it is large enough, it may be okay as long as he has 24/7 access to it. Ours has a roof over it, so I put a cat tree out there (except for winter) and he will hop up in the sleeper. When the temps are really warm, he tends to want to stay in the house, but even on our hot afternoon walks, he will just find a spot in the shade in the yard and lay down, so I carry a large towel with me, so I can sit down. Raiden prefers the cool grass, but I'd rather have the towel.

In the end .... we do what is best for our cats. I sacrifice my time for an hour in the morning and hour in the afternoon, seven days a week, rain, shine, hot, cold, snow, ice. Raiden dictates our travels and how long we actually stay out there. He is now 10 years old and I'm sure we have thousands of more walks in our future. They can be a great time to bond and spend quality time together.

This thread is an eye opener for me.

I bought the harness and was ready to start taking her out this weekend. But after reading this, I'm not so sure.

Does car drives count too if leashed and fastened to a seatbelt?

I replied to your other post Hassaan. It's a long reply and I hope you take the advice to heart! I live on a dead-end street and we have a park two blocks way. Raiden is confident and comfortable walking the 8 blocks total twice a day. We have cars that come by -- he will stop and watch them pass us. He does not like dogs and will lay down until they pass. Humans walking are fine, but if they are jogging and panting, he wants to run the other way. The garbage trucks and street sweeper terrify him. A UPS man walking up the driveway with a package will cause him to want to bolt and he did get out of his leash recently because I did not have it on tight enough for him. After he fought with another cat, I was able to catch him. Ugh! Life with any cat is not easy when you take them for walks. I wish he would be a strictly indoor cat, but that is not going to happen and I'm getting way too old to keep this up much longer.