Gana  Elmina Castle

The Portuguese were the first to arrive. By 1471, under the patronage of Prince Henry the Navigator, they had reached the area that was to become known as the Gold Coast because Europeans knew the area as the source of gold that reached Muslim North Africa by way of trade routes across the Sahara. The initial Portuguese interest in trading for gold, ivory, and pepper so increased that in 1482 the Portuguese built their first permanent trading post on the western coast of present-day Ghana. This fortress, Elmina Castle, constructed to protect Portuguese trade from European competitors and hostile Africans, still stands.

With the opening of European plantations in the New World during the 1500s, which suddenly expanded the demand for slaves in the Americas, trade in slaves soon overshadowed gold as the principal export of the area. Indeed, the west coast of Africa became the principal source of slaves for the New World. The seemingly insatiable market and the substantial profits to be gained from the slave trade attracted adventurers from all over Europe. Much of the conflict that arose among European groups on the coast and among competing African kingdoms was the result of rivalry for control of this trade.

The Portuguese position on the Gold Coast remained secure for almost a century. During that time, Lisbon leased the right to establish trading posts to individuals or companies that sought to align themselves with the local chiefs and to exchange trade goods both for rights to conduct commerce and for slaves whom the chiefs could provide. During the seventeenth and eighteenth centuries, adventurers--first Dutch, and later English, Danish, and Swedish-- were granted licenses by their governments to trade overseas. On the Gold Coast, these European competitors built fortified trading stations and challenged the Portuguese. Sometimes they were also drawn into conflicts with local inhabitants as Europeans developed commercial alliances with local chiefs.

The principal early struggle was between the Dutch and the Portuguese. With the loss of Elmina in 1642 to the Dutch, the Portuguese left the Gold Coast permanently. The next 150 years saw kaleidoscopic change and uncertainty, marked by local conflicts and diplomatic maneuvers, during which various European powers struggled to establish or to maintain a position of dominance in the profitable trade of the Gold Coast littoral. Forts were built, abandoned, attacked, captured, sold, and exchanged, and many sites were selected at one time or another for fortified positions by contending European nations.
Both the Dutch and the British formed companies to advance their African ventures and to protect their coastal establishments. The Dutch West India Company operated throughout most of the eighteenth century. The British African Company of Merchants, founded in 1750, was the successor to several earlier organizations of this type. These enterprises built and manned new installations as the companies pursued their trading activities and defended their respective jurisdictions with varying degrees of government backing. There were short-lived ventures by the Swedes and the Prussians. The Danes remained until 1850, when they withdrew from the Gold Coast. The British gained possession of all Dutch coastal forts by the last quarter of the nineteenth century, thus making them the dominant European power on the Gold Coast.

Fort James- It is likely that this was a Portuguese lodge in the middle of the 16th century probably built around 1576.
Fort Crevecoer (Ussher Fort)- Dutch post built in 1642
Christiansborg Castle- Built in 1640 by the Portuguese as Urso lodge in Accra and after changing hands on numerous occasions it was finally sold to the British in 1850. Since then it has been to official residence of the governors of the Gold Coast and heads of states of Ghana. It's officially closed to the public.
 
Fort Fredensborg- meaning Castle of Peace, was constructed during the years 1736-42.

Fort James
In 1557 the Portuguese built a trading lodge in Accra which the later fortified and enlarged in 1576. However, between 1577 and 1578 the half-built fort was attacked and destroyed by the locals. By 1782 had taken over and rebuilt this fort which the used as a base for attacking the Dutch Fort Crvecoeur. After Ghana gained its independence James Fort was converted for use as a prison.

http://www.ghanaweb.com/GhanaHomePage/history/slave-trade.php