Hi Leanne,
Unfortunately, the map was taken from the book. However, this link should take you to a blog which uses the exact same map:
http://3.bp.blogspot.com/-Zksxcvg9kpw/T9Jp9NDtpFI/AAAAAAAACWk/d6ZXFwv_QnM/s1600/richards_map_of_ostia+copy.jpg
Here is a model for you to use.
Close to the banks of the River Tiber in the Roman city port of Ostia, a large villa belonging to the Manus family could be found. In this house lived Gaius Manus, the only son of Marcus Manus. Marcus Manus was one of Ostia’s richest merchants. Like all wealthy Roman boys of twelve, Gaius spent a great deal of time with his tutors. His father hoped that this education would one day allow him to become someone of importance in both Ostia and the Roman Empire. From his room on the second floor, Gaius would often spend hours reading about the great Roman leaders of the past. Being a keen problem solver, Gaius took a particular interest in the life and times of Julius Caesar. He loved reading about Caesar’s battles against the Goths and Celts - how Caesar had used his intelligence to repeatedly defeat these barbaric people’s. It was a hot, still afternoon in Ostia and Gaius was reading about Caesar’s invasion of Britannia. In an instant, Gaius’s peaceful reading came to an end as a scream cut through the air… In the triclinium on the ground floor, Gaius’s mother was lying prostrate on a couch surrounded by half a dozen slaves. “Oh mater, what’s happened?” “Awful! Dreadful! What will I do?” Sobbed Helena, Gaius’s mother. Gaius was used to his mother suddenly breaking down into tears for no reason but this was different somehow. He had never seen his mother so distraught before. It was like she had been told that the fires of Vesuvius had erupted and there was nowhere to go. “Mother. What is it? Why are you so upset?” “I have lost it!” “What have you lost?” “My jewels...they are gone!” Gaius’s face turned pale as he saw his mother clutching at the bare skin around her neck. She was talking, of course, about the Corinthian loop. A necklace made of Greek gold and Nubian emeralds. It had been a gift from his father on their wedding day. “What happened mother?” His mother slowly turned her tear filled eyes towards him and began to recount everything that had happened that day since she had first left the house. As Gaius listened to the story, he carefully kept a record of anything which might help his mother to reclaim her lost gems. It seemed that his mother had taken her usual route to the market. She had visited the baker where she had ordered next months supply of bread and flour. After her journey to the bakers, she had been rudely stopped by a toga salesman who had insisted she buy some of his newest clothing. In fact at one point this ruffian had actually laid hands on her. As fast as she could, she had left the market and returned home. Listening intently, Gaius realised that there weren’t any toga salesman or shops in that area of Ostia. “Mother, was there anything unusual about this salesman?” He asked while scanning his mother’s gown. “Well, now you mention it. He did have a large scar under his eye. And his hands were covered in red dust.” She said in a faraway voice. Staring at his mother’s toga, he could see dusty red fingerprints near to her neck. That’s it! That’s when he knew who the thief was and where to find him. It was clear that the thief must have come from the potter’s district near the warehouses on the seafront. After making sure his mother was calm and settled, Gaius went to retrieve a small leather sack from his room on the second floor. Slipping quietly through the front door of the atrium, Gaius had begun his quest to locate the Corinthian loop. It was the ninth hour as Gaius left the house. He decided to take the Via Cassia to the Marina as this was the fastest way to get there. Following the road, it took about an hour to reach the warehouses. Gaius asked a soldier, who seemed to be half asleep, where the pottery shops could be found. The soldier yawned and pointed towards a group of buildings next to the warehouses. After thanking the warrior for his help, Gaius made his way towards these shabby looking buildings which overlooked the sea. As he walked across the road, he had already worked out which shop the thief had come from. He knew this because the shop he was looking at was the only one which sold Tilean vases (a type of vase which used a deep red colored dust). The emporium was old and rundown with a broken door. As Gaius carefully opened the door, a monstrous dog came bounding towards him… As quick as a flash, Gaius dived to his right. The dog skidded past. Glancing around him, Gaius saw a small doorway at the back of the room. Sprinting with all his might, he just made it through before the dog had an opportunity to make a meal of his leg. Panting for breath, the young boy took in his surroundings and that’s when he saw it...The necklace was lying on the large, round belly of a sleeping man. A man with a deep scar running down the right side of his face. Amazingly, the man hadn’t woken up during Gaius’s escape from the dog. Carefully, Gaius reached forward and slowly removed the necklace from on top of the man’s stomach. Then he made his way towards a small window at the back of the shop. The window was covered with a tatty sheet which Gaius pulled open. Behind the window, was a small, dark alley. Without daring to look around, he climbed through the window and into the cramped street. After peering back through the window to make sure the man was still sleeping, Gaius quickly made his way back to the Via Cassia. It took more than an hour for Gaius to finally return home. As his hand touched the solid frame of his front door, Gaius let out a deep sigh filled with relief. He had done it! Gaius Manus had located and retrieved the Corinthian Loop! Opening the door, he quietly made his way to the triclinium where he knew his mother would be sleeping. Gently lifting the necklace from his leather sack, he carefully placed it next to the dozing body of his mother. After ensuring that his mother wouldn’t accidentally knock the object from her couch, Gaius headed back up to his room. It was a hot, still afternoon in Ostia and Gaius was reading about Caesar’s invasion of Gaul when a loud piercing cry filled the sky outside. Placing the scroll in a leather case, Gaius collected his leather bag and made his way towards the source of the sound...
I hope this helps!