[5] The New Statistical Account of Scotland attributed the name Dee as having been used as early as the second century AD in the work of the Alexandrian geographer Claudius Ptolemy, as Δηοῦα (=Deva), meaning 'goddess'.[9] The river is then joined by a tributary coming from the Pools of Dee in the Lairig Ghru, and flows south down the Lairig Ghru between Ben Macdui and Cairn Toul, tumbling over falls in the Chest of Dee on its way to White Bridge and the confluence with the Geldie Burn, at which point it turns east.[9] At Linn of Dee the river passes east through a 300-metre natural rock gorge,[2] a spot much favoured by Queen Victoria during her stays at Balmoral.Through Deeside the river passes Braemar, Balmoral Castle, Ballater, Dinnet, Aboyne, and Banchory reaching the sea at Aberdeen.[9][11] The tidal limit is just above Bridge of Dee which was built about 1720; it carries the main A90 trunk road from Aberdeen to the south.[14] The entire length of the Dee is defined as a Special Area of Conservation (SAC) due to its importance to salmon, otters and freshwater pearl mussels.[23] The A93 road runs west along the north bank of the river from Aberdeen to Braemar before it turns south, leaving Deeside, to climb to the Glenshee Ski Centre at Cairnwell Pass and then onwards to Perth.[25] The line was not extended beyond Ballater to Braemar as this would require it to run close to Balmoral, leading to objections from Queen Victoria.