The most famous landmark of Gibraltar, that greets you as soon as you land has a lot to offer. It would probably take most people a whole day to fully explore the whole Rock and would require some hiking to get to the top. However there are other options that allow you to see the main sites. These include a cable car (currently out of use until 2028), a taxi and guide and a shuttle bus. Some of the main sites that in my opinion are must see's at the rock are as follows. First up is the Pillars of Hercules. Here you can lean about the myth behind the name while looking out across the sea to both Spain and Morocco. Next up is a personal favourite. St Michaels cave. Here enjoy a 10 min long light show that really showcases the spectacular forms in the cave. You also may get your first encounters with the infamous Barbary Macquet's (the only place in Europe you will see wild monkeys). As you continue up you can walk on the skywalk to see the views from a completely new persecutive as you make your way to the Apes den (a feeding area for the monkeys). Just watch out as these monkeys as not shy around people and will go into bags and jump on heads. Further up the rock you will find the WW2 and Siege tunnels which really make Gibraltar's military history come alive. I personally didn't realise how many or how long these tunnels were until i was in them. In the WW2 tunnels there is also a unique view point through the rock over the city which is worth the effort to see. The other must see at the rock in my opinion is the Moorish castle that stands guard over the city.