The Grade 1 Listed Milford Mill Bridge dates from the early Tudor period of the late 15th Century. The bridge is made of dressed limestone with two arches linked by a causeway and it crosses the River Bourne. If you look carefully, you'll note that the western archway is semi-circular, while the other arches are pointed. There are then cutwaters with weathered heads between each arch and roll-moulded and hollow chambered continuous string courses at road level.
The bridge was painted by John Constable in 1836: http://collections.vam.ac.uk/item/O1041855/milford-bridge-with-a-distant-watercolour-john-constable/
The bridge replaced the ford that was on the main route between Winchester and Salisbury and the now ruined Clarendon Palace (a 2.5km, easy walk away that I would certainly recommend! Go to see the Llamas in the field there too!). As you face the bridge, the field to the left is the deserted medieval village of Meleford, as it was called in the Domesday book of 1066.
The cache itself is a small lock'n'lock box. You do not need to disturb the bridge or get close to the water to find this cache. The water can be deep and fast flowing, so make sure you (and especially children and pets) stay away from the edge. There is also no footpath to cross the bridge, but there is a wide verge to cross over on foot on the roadway. This is a common route and traffic only flows one direction at a time due to the traffic lights. Again, be aware of traffic, especially with Geokids and Geopets!
Please replace the cache carefully and ensure it's well-hidden!