Dublin city

Dublin Castle (Irish: Caisleán Bhaile Átha Cliath) off Dame Street, Dublin, Ireland, was until 1922 the seat of British rule in Ireland, and is now a major Irish government complex. Most of it dates from the 18th century, though a castle has stood on the site since the days of King John, the first Lord of Ireland. The Castle served as the seat of English, then later British government of Ireland under the Lordship of Ireland (1171–1541), the Kingdom of Ireland (1541–1800), and the United Kingdom of Great Britain and Ireland (1800–1922). Upon establishment of the Irish Free State in 1922, the complex was ceremonially handed over to the newly formed Provisional Government led by Michael Collins.

Christ Church Cathedral is a cathedral church of the Church of Ireland. The Church of Ireland is a provence of the Worldwide Anglican Communion. The two primates of the province are the Most Revd Alan Harper (Armagh and Tuam) and the Most Revd Dr Michael G. St. A. Jackson (Dublin and Cashel).

Taken from: http://www.christchurchdublin.ie/

Dublinia is located in a 19th century neo-Gothic building that housed the Synod Hall of the Church Of Ireland until 1983. The building was erected on the site of an older, 17th century church of which only the bell tower survived. The tower is now part of the Dublinia museum. The building is connected with historic Christchurch Cathedral on the opposite side of St Michael's Hill via an enclosed pedestrian bridge. The museum opened its doors in 1993 and added its permanent exhibition The Viking World in 2005.

Lose yourself in Viking & Medieval Dublin. 3 exhibitions in Dublinia include Viking Dublin (explore the Viking times of Dublin, its settlement, what life is like on a Viking warship, the clothing, what it is like to be a slave, and how cramped Viking homes were), Medieval Dublin (following history from Strongbow to the Reformation, what warfare and crime/punishment was like in the times, and about the Black Death) & History Hunters Exhibition (gain insight into modern archaeological practices and current digs in the area, the technology they use, and the tools they utilize). 

St Patrick’s Cathedral is named after St Partick, the patron saint of Ireland. It is said that he baptised converts in a well nearby. There has been a church on this site since the 5th century but the present building dates from 1191. In 1224 the church got cathedral status. The Cathedral was founded in 1191 and it best know for it's famous Dean Jonathan Swift from 1713 to 1747. Also most famous for performing Handel's Messiah here in 1742. Inside you will find a permanent exhibition that celebrates St Patricks life in the city.

Gino’s is owned and run by two men who have been in the ice cream business for the past 20 years. The Gino’s concept reflects the Italian ‘la dolce vita’ through our casual offering of coffees, drinks and crepes as well as our product line of artisan gelato. The shop is located at Grafton street.

Taken from: http://www.ginosgelato.com/

The Spire of Dublin, officially titled the Monument of Light (Irish: An Túr Solais) is a large, stainless steel, pin-like monument 121.2 metres (398 ft) in height, located on the site of the former Nelson's Pillar on O'Connell Street in Dublin, Ireland.

Temple Bar is one of the oldest areas in Dublin. It is full of bars, restaurants, and tons of people. The cobbled streets and architecture are definitely worth a wander during the day and the lively nightlife is worth a stop if that is the reason you are in Dublin.

Ha’penny bridge this bridge is one of the oldest bridges made in cast-iron structure and it was constructed in 1816. This bridge is the oldest bridge that crosses the river Liffey. The original name was Wellington Bridge but it soon became known as the Ha’penny bridge, since people had to pay half a penny to cross the bridge until the year of 1919.

Photo credit: Nicitoyou

Sources/info from : http://www.virtualtourist.com/Things_To_Do-Dublin