import json
from html import escape

with open('data.json') as data_file:
    data = json.load(data_file)

with open('Megaliths.gpx', 'w') as gpx_file:
    gpx_file.write('''<?xml version="1.0" encoding="UTF-8"?>
<gpx xmlns="http://www.topografix.com/GPX/1/1" 
     version="1.1" 
     creator="megalithosm" 
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
     xsi:schemaLocation="http://www.topografix.com/GPX/1/1 http://www.topografix.com/GPX/1/1/gpx.xsd">
    <metadata>
        <name>Megalith sites</name>
        <author>
           <name>Jude Southworth</name>
        </author>
    </metadata>''')

    for poi in data:
        gpx_file.write(
            '''
    <wpt lat="{}" lon="{}">
        <name>{}</name>
        <type>{}</type>
        <url>{}</url>
    </wpt>'''.format(poi['lat'], poi['lng'], escape(poi['name']), poi['type'], poi['url'])
        )
    gpx_file.write('</gpx>')