The fort was designed by engineer Van Buren and at the time of construction was square and had four bulwarks on the corners measuring along the outer bulwarks 132 roeden. Apparently the Dutch constructed a small redoubt to protect the workers (see image 3). In the middle of June 1631 a hornwork was constructed and the fort was ready by the end of the month.
Part of the building material came from a small island to the north that was stripped of its vegetation. Some 400 people were living in the fort. The report of Richshoffer in October 1631 indicates that construction works continued, the soldiers were probably constantly trying to dig out the moat that was receiving sand that came in with the sea. The fort was adapted when it was attacked in 1632. The wall was raised four and a half feet on the northwestern side and some trenches were also made in case of an attack. These works were probably made with sand from the beach. The garrison was probably diminished, but there is no information until 1638 when the fort is reported to be square with four bulwarks and having been repaired recently. But it was completely without a moat and was lacking palisades, which would have to be made. The moat was to be dug out and a contra-escarpe was to be built on the outside. North of the fort there was a hornwork.
Apparently all the bulwarks had been closed at the time that the drawing shown in image 5 was made. There is shown a moat and a hornwork, but it is not known if this drawing was a representation of an actual situation or a plan. The report of 1640 described the Fort also as a square fortress with four bastions. It mentioned that the bastions were constructed reasonably high. It also referred to the problematic moat that was only partly in place and was described as being shallow and dry. The fort was now surrounded by a strong pilework. The garrison of the fortress at the time was composed of a total complement of 182 soldiers.
The garrison of Fort Orange in August 1643 had been reduced to only 71 soldiers, the economic crisis in Dutch Brazil forced the WIC to take drastic measures. The lack of finances meant that there probably was no money to undertake repairs to the fort. The artist Frans Post produced several images of the island of Itamaracá, but no detailed image of the fort by his hand was published. The unpublished image that Post produced of Fort Orange was probably the basis for images that were published later, like the one shown in image 6. On one of these images the Fort is depicted in detail and there are several aspects that seem quite different from the ground plan reproduced as image 5. The position of the latrine does not match that of the ground plan and it seems that the eastern bulwark is lacking.The gate built of brick masonry that Nieuhof mentioned, is clearly visible on the sea-side according to the ground plan of image 5. The large square building with the flag is difficult to place on the ground plan. It is difficult to determine to what extent this image represents the actual situation of the Fort at the time (image 6).
The last detailed description that was consulted dates from 1646 and described the fort as having a solid wall and a parapet all around made of wood. At the time there were no palisades, but their construction had already been contracted. The moat continued to be shallow. The hornwork was partly demolished. The interior had a powder house that was in a reasonable state and there were living quarters.
This report also mentioned the gate as being vaulted with masonry. The garrison had probably had been increased, but its exact strength is difficult to calculate as there are no specific lists for the Fort, but only for the island as a whole. It is reasonable though that some 200-250 soldiers out of the total of approximately 470 on the whole of Itamaracá, stayed at Fort Orange.