Under a pristine blue sky with the Sierra Nevada mountains in the background, the historic Moorish palace -- and Europe's jewel of Muslim architecture -- was once again opened to visitors, although with strict health and security regulations in place.

"I feel very proud to be here and to be the first visitor allowed into the Alhambra," said Mariana Castro Mendoza, a 36-year-old Mexican living in Granada, where the Alhambra is located. 

To mark the occasion, she was allowed to ring the bell in the Torre de la Vela watchtower which dominates the site, saying it gave her "a great sense of pride" with the bell "a symbol of hope for everyone". 

With travel regulations still in place until June 21, only locals were able to visit the site which was once home to the Moorish kings and is now one of the world's largest open-air museums of Islamic architecture.

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Normally packed with visitors from Spain and beyond, the Alhambra is likely to see the crowds returning from next week when Spain's borders reopen.  

And from July 1, the frontiers will be open to all international visitors, although strict security measures will remain in place.

At the entrance, sanitizing gel was on hand and both staff and visitors were wearing masks, with spacing arrows on the floor to avoid crowding and signs reminding people to respect the two-metre security distance. 

"This is a happy day because we're seeing visitors again," said Rocio Diaz who heads the trust that runs the site. 

For now, the Alhambra can only let in up to 50 percent of its capacity of 4,250 visitors, with Diaz saying they had sold "around 1,000 tickets" on Wednesday. 

"The Alhambra is always beautiful but now, with fewer people, I feel like it shines even more," said Mendoza, the Mexican visitor. 

A World Heritage Site whose name is Arabic for "the red one", the Alhambra is a monumental complex that incorporates ornate Islamic palaces, a fortress and the Renaissance-style Carlos V Palace.

Last year, around 2.7 million visited the site, drawn by its interiors covered with myriad Arabic inscriptions and intricate geometrical patterns, and its beautiful gardens and stunning views.

The Alhambra was the seat of the Nasrid dynasty, the last Muslim rulers in the Iberian Peninsula, that ruled Granada from 1238 until Catholic monarchs Ferdinand and Isabella reconquered the city in 1492.