The 16th-century gatehouse is on the inland side of the Nether Bailey, and comprises twin D-plan towers flanking an arched entrance passage.
Formerly the passage was defended by a portcullis and a double set of doors, with guard rooms either side.
Over the entrance are a series of rooms which may have served as accommodation for the castle's keeper.
Collapsed masonry surrounds the gatehouse, dating from its destruction after 1690.

The Nether Bailey, the main focus of activity in the castle since around 1400, is anchored at its northern tip by the Grant Tower, the main tower house or keep.
The tower measures 12 by 11 metres (39 by 36 ft), and has walls up to 3 metres (9.8 ft) thick.
The tower rests on 14th-century foundations, but is largely the result of 16th-century rebuilding.
Originally of five storeys, it remains the tallest portion of the castle despite the southern wall collapsing in a storm in the early 18th century.
The standing parts of the parapet, remodelled in the 1620s, show that the corners of the tower were topped by corbelled bartizans (turrets).
Above the main door on the west, and the postern to the east, are machicolations, narrow slots through which objects could be dropped on attackers.
The western door is also protected by its own ditch and drawbridge, accessed from a cobbled "Inner Close" separated from the main bailey by a gate.
The surviving interior sections can still be accessed via the circular staircase built into the east wall of the tower.
The interior would have comprised a hall on the first floor, with rooms on another two floors above, and attic chambers in the turrets.
Rooms on the main floors have large 16th-century windows, though with small pistol-holes below to allow for defence.

To the south of the tower is a range of buildings built against the thick, buttressed, 14th-century curtain wall.
The great hall occupied the central part of this range, with the lord's private apartments of great chamber and solar in the block to the north, and kitchens to the south.
The foundations of a rectangular building stand on a rocky mound within the Nether Bailey, tentatively identified as a chapel.
The 16th-century gatehouse is on the inland side of the Nether Bailey, and comprises twin D-plan towers flanking an arched entrance passage. Formerly the passage was defended by a portcullis and a double set of doors, with guard rooms either side. Over the entrance are a series of rooms which may have served as accommodation for the castle's keeper. Collapsed masonry surrounds the gatehouse, dating from its destruction after 1690.
The Nether Bailey, the main focus of activity in the castle since around 1400, is anchored at its northern tip by the Grant Tower, the main tower house or keep. The tower measures 12 by 11 metres (39 by 36 ft), and has walls up to 3 metres (9.8 ft) thick. The tower rests on 14th-century foundations, but is largely the result of 16th-century rebuilding. Originally of five storeys, it remains the tallest portion of the castle despite the southern wall collapsing in a storm in the early 18th century. The standing parts of the parapet, remodelled in the 1620s, show that the corners of the tower were topped by corbelled bartizans (turrets). Above the main door on the west, and the postern to the east, are machicolations, narrow slots through which objects could be dropped on attackers. The western door is also protected by its own ditch and drawbridge, accessed from a cobbled "Inner Close" separated from the main bailey by a gate. The surviving interior sections can still be accessed via the circular staircase built into the east wall of the tower. The interior would have comprised a hall on the first floor, with rooms on another two floors above, and attic chambers in the turrets. Rooms on the main floors have large 16th-century windows, though with small pistol-holes below to allow for defence.
To the south of the tower is a range of buildings built against the thick, buttressed, 14th-century curtain wall. The great hall occupied the central part of this range, with the lord's private apartments of great chamber and solar in the block to the north, and kitchens to the south. The foundations of a rectangular building stand on a rocky mound within the Nether Bailey, tentatively identified as a chapel.
Urquhart Castle