Picturesque feature added to the 19th century designed landscape for the cultivation and display of rare trees. Some Lawson cypress and deciduous trees are present, but western hemlock, larch, sycamore and beech predominate. Little evidence of the arboretum survives as many of the original trees were felled to make way for commercial planting. Between Hill Head Wood and Fugarfield Wood is an area of fine deciduous trees including Spanish chestnut and yew. These seem to form an avenue which may have led to the arboretum.

A natural dell runs through the north and east edges of the Greenhouse Walks woodland. The stream at its base is now dry. An outlet for the stream is covered by a sandstone arch, which is visible at the south-east of the woodland. The present line of the stream differs from the 1785 plan. It has been developed into part of the ornamental garden by the additional of a gravel bed and rock edging.

Two stretches of ha-ha. One at the woodland known as the Greenhouse Walks (larch planted in the 1960s with older planting on the periphery) stands on a natural hill which has views south-east towards the edge of Gateshead and across the parkland. A ha-ha flanks the west and south edges of the woodland, separating it from the parkland. Greenhouse Walk has been almost entirely replanted for commercial purposes by the Forestry Commission. It is largely inaccessible due to the loss of footpaths and due to the post and wire fence around it. The second stretch is along the south edge of the walled garden also defined by a low sandstone wall. A bridge across the ha-ha to the head gardener's cottage is still evident and the entrance is marked by two ornamental stone bollards. The ha-ha is in good condition.

There is a steeply sloping bowl shaped hollow in the woodland which once housed a gasometer. The gasometer and gas house, a short distance away to the south are shown on the OS second edition map.

To the south-east of the stable block is a large pollarded lime, some 5m in diameter, indicating a tree of at least 300 years old. To the east there are remains of some stone buildings and a fallen pair of stone gate piers, now overgrown by sycamore and ground flora. A bowl shaped hollow was once a pond. Building remains are scattered throughout the north-west section of the woodland. Undulating ground may be evidence of former industrial activity.

An old path runs from the carriage drive to the South Tower along a yew lined walk. There is a pile of loose stone at the stone end of this walk, perhaps indicating that a building once occupied this spot. It might have been a 'seat' or garden building to take advantage of the excellent views across the parkland. Or it might be linked to deer husbandry, agriculture or industry.

There were two carriage drives into the park. The line of the former 18th century carriage drive ran from Watergate Bank and is visible as a linear clearing through the woodland. The other drive is still extant as an access road and links the castle and Trench Hall to Watergate Bank at North Lodge and the castle to Coach Road at South Lodge. The woodland belt runs parallel to this carriage drive and an avenue of yew trees flanks it as it turns north towards the Butter Cross.

To the south-east of the stable block are two small stone and brick structures. The first is orientated north-west to south-east and measures 4.7m x 6.5m. It is built of coursed sandstone rubble with stressed blocks at the arris, and has a single doorway in the western side. The function of the building is not known, but it may have housed either a pump for the water supply or a regulator for the gas works situated further south along the main carriage road. A second smaller structure is orientated north-west to south-east and measures 3.25m x 2m. It is built of coursed and cur sandstone blcoks with an internal brick lining. The function of the building is not known. It is of higher quality than the larger building. It may have housed some form of utility for the stable block or house.

The icehouse lies to the north of the North Tower. It is almost certainly contemporary with the tower's brick lined cellar. Externally it comprises a rectangular earth mound orientated east to west and measuring 5m x 12m. It abuts the north wall of the tower. The structure is entered via a stone-lined L-shaped passageway. At the end of the passageway there are fittings for two sets of rectangular doors. This second doorway leads into a brick-lined chamber below ground level. The double doors would have kept the room as cold as possible. Access into the chamber is via a set of steep wooden stairs. The brick-lined barrel vaulted chamber is 3-4m deep with a small square delivery hatch in the east wall. Below the hatch is a ramp made from two angled timbers which have been recently used to drop masonry blocks into the interior. The timbers are not original. Recorded by NAA in 2014.

Remains of an ornamental octagonal pool, largely intact but in poor condition and in danger of deterioration. With central stone base, probably a fountain.