Grand Piano Legs
Piano legs are in three main categories:
- 3 turned legs: mainly on older pianos to about 1900
- 3 Square tapered legs: gradually replaced turned legs as the main style of legs post 1900.
- 6 "gate legs" or twin legs: found mainly from about 1910 to 1940
Modern pianos mainly have 3 turned tapered legs. 
Concert pianos and those in institutions which require the piano to be moved around are often put on "A frames" though modern concert castors don't need this device.

Legs: Above pictured is from Steinway model A grands, approx 1885-1905 and is appropriately called an "elephant leg"
Steinway model A grand approx 1900-1920 with 'gate' legs	Bosendorfer model 275 grand with turned legs approx 1910 - 1925	Broadwood grand with turned legs approx 1890 - 1915
Bechstein grand with turned legs approx 1890  - 1910	Monington & Weston cabriole leg approx 1920 - 1940	Yamaha C3