Looks good. Will be even better when it has lots of grass and weeds growing

The city can be full of dangerous (to tiny torts) raccoons, possoms, cats, dogs, crows, etc. So don't get too over confident in the safety thing... I saw more raccoons when I lived in Seattle than I do now that I live an hour away...

Also, don't underestimate the climbing ability of torts. Most folks built a lip around the top edge and especially the corners to prevent climbing over. I've heard from many folks who have come home to find their tort missing and climbed the wall they always thought was safe.

This is a great site for tort owners:
http://tortoiseforum.org/index.php

Also, do you have a long term plan? Won't take long until that space is way too small. In a few years you'll need a full yard just for the tort...